IRLF 


ENGIN. 
LIBRARY 


B    3    1EM 


CON 


Lesley 


Bruce  &  Banning 

New  York 


TX  OF  C/ 
LIBRABY 
OF  CIVIL 


Gift   of  Mrs,   Edv/in  H.  Warner 
•from  her  husband's   library, 

•January  1928 


•Lngineerinfir 

T    it-.».r.»>,. 


UNIVERSITY  OF  CAOTORNIA 

fc&    AIVIMENT  OF  CIVIl-  ENGINEE^ttfcl® 


UNIVERSITY  or  CALIFORNIA 

^WPARTMENT  OF  CIVTL  ENQIMEERttW 
BERKELEY.  CALIFORNIA 


I-1* 


THE    HIGHEST  COMPLETE  CONCRETE   BUILDING  IN   PHILADELPHIA;    PLANT  OF  THE   KETTER- 
LINUS    LITHOGRAPHIC  MANUFACTURING    COMPANY 


CONCRETE     FACTORIES 

An  illustrated  review  of  the  principles  of  construc- 
tion of  reinforced  concrete  buildings •,  includ- 
ing reports  of  the  Sub-Committee  on 
Tests ,  the  U.  S.  Geological  Sur- 
vey and  the  French  Rules 
on     Re  i nfo  reed 
Concrete 


COMPILED 
By 

ROBERT    W.   LESLEY, 

Associate  Am.  Soc.  C.  E. 


Published  for  the 
CEMENT  AGE  COMPANY, 

By 

BRUCE  &  BANNING, 
New  York. 


Engineering 
Library 


TABLE   OF   CONTENTS 


Concrete    Plant   of  the    Ketterlinus    Litho- 
graphic Manufacturing  Co.       .         Frontispiece 
Introduction       ......        6 

Report  of  the  Sub-Committee  on  Tests        .      10 
United  States  Advisory  Board  on  Fuels  and 

Structural  Materials  .  .  .  -19 
French  Rules  on  Reinforced  Concrete  .  27 
Reinforced  Concrete  Construction  .  .  42 
Concrete  in  Factory  Construction  .  ..7.1 
A  Surface  Finish  for  Concrete  .  .  .  103 
Value  of  Concrete  as  a  Structural  Material  .  112 
Miscellaneous  Illustrations  .  .  .  133 


785318 


INTRODUCTION 

The  subject  of  concrete  and  reinforced  concrete  is  one  of  the  most 
important  matters  that  is  now  before  the  American  public.  So  im- 
portant has  it  been  considered  by  those  connected  with  engineering, 
that  the  leading  societies  in  this  field  have  associated  themselves  in  the 
creation  of  a  Joint  Committee  on  Concrete  and  Reinforced  Concrete, 
the  members  of  which  Committee  are  representatives  of  the  following- 
societies  : 

American  Society  of  Civil  Engineers; 

American  Society  for  Testing  Materials; 

American  Railway  Engineering  &  Maintenance  of  Way  Association, 

Association  of  American  Portland  Cement  Manufacturers. 

In  addition  to  this,  the  following  organizations  are  lending  their  hearty 
co-operation  in  the  work. 

National  Board  of  Fire  Underwriters; 

National  Fire  Protection  Association ; 

The  Concrete  Block  Machine  Manufacturers  Association,  and  the 

National  Association  of  Cement  Users. 

The  Work  of  the  Committees 

This  Committee  on  Concrete  and  Reinforced  Concrete,  as  is 
well  known,  has  been  at  work  for  nearly  two  years  endeavoring  to 
arrive  at  some  definite  conclusions  on  the  important  subjects  entrusted  to 
their  care.  It  has  been  most  fortunate  in  being  able  to  secure,  not  only  the 
co-operation  of  the  leading  colleges  of  the  United  States  in  its  research 
investigations,  but  also  the  co-operation  of  the  United  States  Advisory 
Board  on  Fuels  and  Structural  Materials,  which  has  a  splendidly  equipped 
laboratory  at  St.  Louis.  The  importance  of  the  work  was  recognized  by 
the  United  States  Government  in  a  practical  way  by  an  appropriation  of  one 
hundred  thousand  dollars,  for  the  purpose  of  carrying  on  the  experiments 
required.  The  scope  of  the  work  is  fully  detailed  in  the  report  of  the 
Sub  Committee  on.  Tests  which,  with  its  introductory  matter,  fully 
explains  the  field  to  be  covered,  the  purpose  of  the  investigations,  and  gives 
with  great  accuracy  the  subjects  to  be  investigated  in  the  line  of  concrete 
and  reinforced  concrete. 

[6] 


INTRODUCTION 

This  has  been  followed  within  a  recent  period,  by  the  adoption  by  the 
Advisory  Board  on  Structural  Materials  of  the  U.  S.  Geological  Survey  of 
a  program  for  a  full  investigation  of  cement  blocks,  thus  covering  in  the 
investigations  to  be  carried  on  at  the  Government  laboratory  at  St.  Louis 
the  two  great  fields  of  practical  use  to  the  community  at  large. 

It  is  needless  to  say  that  the  program  involves  a  long  period  in  its 
accomplishments — involves  practical  research  and  investigation  into  the 
subject  in  all  its  details,  beginning  with  the  selection  of  cements,  the  sands 
and  the  aggregates,  and  going  through  the  whole  field  of  the  methods  of 
constructing  block  monolithic  and  reinforced  concrete  structures. 

The  examinations  into  the  making  of  beams  of  various  characters; 
into  the  making  of  columns;  into  the  proper  methods  of  reinforcing  these 
forms  of  construction  and  finally,  the  investigation  into  cement  blocks 
covers  a  large  field  and  is  but  a  beginning.  It  is  hoped  that  when  proper 
formulae  have  been  arrived  at  in  all  these  various  branches  of  the  art,  that 
such  a  standard  for  concrete  and  reinforced  concrete  and  cement  block 
construction  will  have  been  developed,  that  building  inspectors  all  ov^r 
the  country  and  leading  engineers  in  all  parts  of  the  United  States  will 
adopt  and  put  in  force  the  methods  suggested.  These  methods,  however, 
will  necessarily  be  accompanied  by  the  outline  of  a  plan  to  secure  the  proper 
inspection  of  the  structures  to  be  erected,  thus  securing  through  the  work 
of  the  committee  and  of  the  National  Advisory  Board,  absolute  standardiza- 
tion of  concrete  and  reinforced  concrete  and  cement  block  construction, 
subject  to  the  most  approved  methods  and  the  most  rigid  inspection. 

The  National  Advisory  Board  on  Fuels  and  Structural  Materials  held  a 
meeting  in  Washington  in  December,  where  the  work  of  the  laboratory  was 
presented  in  a  brief  way,  and  where  it  was  shown  that  there  are  now  under 
construction  at  the  St.  Louis  Laboratory  more  beams,  girders  and  columns 
than  hitherto  have  been  made  in  laboratory  work  in  the  United  States,  so 
far  as  official  records  show. 

The  investigations  into  sands  and  aggregates  are  also  on  the  largest 
possible  scale,  and  at  the  Government  Laboratory  at  St.  Louis  to-day 
there  are  at  least  fifty  men  employed  in  the  work,  and  after  the  first  of  the 
year  it  is  expected  that  this  number  will  be  increased  to  one  hundred,  the 
purpose  being  to  secure  in  the  shortest  possible  time,  the  fullest,  clearest 
and  most  definite  results. 

French  Rules  on  Reinforced  Concrete 

In  connection  with  this  work,  the  Committee  of  the  Engineering  Socie- 
ties on  Concrete  and  Reinforced  Concrete  had  before  them  at  their  last 
meeting  in  New  York  on  the  T3th  of  December,  1906,  the  French  Rules 
on  Reinforced  Concrete  which  were  published  in  the  November  number  of 
CKMEXT  AGE.  The  work  of  the  French  Committee  was  highly  appreciated 
by  the  Joint  Committee  and  the  brief,  succinct  and  careful  way  in  which 
they  arrived  at  their  results  was  greatly  praised. 

[7-3 


REINFORCED  CONCRETE 

The  work  of  nearly  four  years,  of  a  Committee  comprising  leading 
French  engineers  both  in  civil  life  and  government  service  and  leading 
French  experts  on  concrete  and  cement — the  report  of  the  French  Committee 
is  deserving  of  the  highest  commendation  and  will  no  doubt  be  of  great 
use  in  clearing  much  of  the  brush  away  on  many  subjects  now  before  the 
American  Joint  Committee  and  the  National  Advisory  Board.  These  Rules 
are  published  in  this  volume  for  the  purpose  of  giving  the  public,  at  the 
present  time,  the  methods  governing  reinforced  concrete  in  the  nation 
which  was  among  the  pioneer  nations  to  use  this  form  of  construction — a 
nation  which  ten  or  fifteen  years  ago  was  in  the  forefront  of  reinforced 
concrete  work  and  which  is  to-day  doing  work  on  the  most  approved  lines 
and  of  the  greatest  importance. 

With  such  a  system  as  is  advocated  under  these  Rules,  or  with  such 
systems  as  will  no  doubt  be  recommended  by  our  own  Advisory  Board  and 
our  United  States  American  Joint  Committee  of  Engineering  Societies  on 
Concrete  and  Reinforced  Concrete  it  will  be  possible  to  secure  work  of  per- 
manence, strength  and  uniformity  in  this  important  art  of  concrete  construc- 
tion. 

Following  these  French  Rules  will  be  found  descriptions  of  various 
systems  of  reinforced  concrete  used  by  leading  concerns  making  a  spec- 
ialty of  this  form  of  construction.  They  embrace  a  number  of  systems  that 
have  been  in  use  many  years  and  with  which  much  good  work,  under  the 
most  practical  methods,  has  been  produced. 

The  results  of  the  work  done  by  many  of  the  companies  having  these  var- 
ious systems  for  reinforcing  concrete,  is  shown  in  the  following  article  on  con- 
crete in  factory  construction.  This  article  is  one  of  the  most  complete  ever 
prepared  on  this  important  subject  and  is  replete  with  descriptions  of  many 
prominent  factory  buildings  and  is  illustrated  by  photogravures  of  the 
work  done  in  the  line  of  manufacturing  establishments  in  all  parts  of  the 
country,  including  every  type  of  manufacturing  business. 

The  Surface  Finish  of  Concrete 

While  the  illustrations  do  not  show  the  beauties  that  can  be  developed 
in  the  surface  finish  for  concrete,  the  fact  that  this  material  is  adaptable  and 
can  receive  a  beautiful  architectural  finish  is  shown  by  Mr.  Quimby's  article 
on  the  Surface  Finish  for  Concrete.  The  illustrations  which  accompany 
this  brief  communication  are  so  beautiful  as  to  have  created  general  interest 
in  engineering  and  architectural  circles  everywhere,  both  in  this  country  and 
abroad.  They  show  what  can  be  done  with  a  material  that  has  hitherto  been 
supposed  to  represent  a  plain  gray  surface,  without  shadow  and  without  light, 
and  how  beautiful  concrete  can  be  made  when  properly  used  and  when  pro- 
perly finished. 

The  Views  of  Leading  Engineers  and  Architects 
A  symposium,  representing  the  views  of  leading  engineers,  architects 
and  experts  in  the  field  of  concrete  and  reinforced  concrete,  is  a  proper 

[8] 


INTRODUCTION 

conclusion  to  such  a  volume  as  this.  That  this  new  building  material,  which 
certainly  is  destined  to  take  the  place  of  lumber,  brick  and  stone  con- 
struction in  our  country,  should  attract  the  attention  of  the  leading  minds 
in  engineering  and  architectural  circles,  was  but  the  natural  result  of  the 
importance  that  it  is  attracting  in  the  building  world,  and  that  these  opinions 
collated  from  many  sources  and  representing  many  varying  views,  should 
unanimously  agree  on  the  value,  importance,  durability  and  permanence  of 
concrete  and  reinforced  concrete  construction,  naturally  follows  the 
growth  and  the  success  of  this  new  building  material. 

While  this  little  volume  is  not  intended  to  be  used  or  considered  as 
authoritative  in  the  field  that  it  sets  out  to  cover,  it  is  however  believed 
to  embrace  much  that  is  of  interest  and  much  that  is  valuable  in  the  way 
of  information  on  the  present  state  of  the  art  of  concrete  and  reinforced  con- 
struction; and  if  it  sets  many  new  minds  thinking  on  this  important  sub- 
ject, and  leads  many  new  minds  to  better  methods,  better  inspection,  better 
care  in  the  work,  "the  purpose  of  this  little  volume  will  have  been  accom- 
plished and  the  country  at  large  will  certainly  be  benefited. 

ROBERT  W.  LESLEY,  Associate  Am.  Soc.  C.  E. 


REPORT  OF  THE  SUB-COM- 
MITTEE ON  TESTS 

Made  to  the  Joint  Committee  on  Concrete  and  Rein- 
forced Concrete;  affiliated  Committees  of  Am.  Soc. 
C.  E.j  Am.  Soc.  for  Testing  Materials,  Am.  Ry. 
Engineering  and  Maintenance  of  W^ay  Ass. 
and  the  Assoc.  of  Am.  Portland  Cement 
Manufacturers. 

In  compliance  with  the  resolution  adopted  by  the  Joint  Committee  on 
Concrete  and  Reinforced  Concrete  at  the  meeting  held  in  New  York  on 
October  n,  1905,  your  Committee  on  Tests  desires  to  present  the  following 
report  as  to  the  policy  to  govern  the  future  work  of  the  Joint  Committee,  to- 
gether with  a  program  of  the  investigation  they  propose  making,  with  sub- 
divisions, and  the  plan  of  execution. 

The  Joint  Committee  on  Concrete  and  Reinforced  Concrete  was 
appointed,  primarily,  for  the  purpose  of  providing  through  the  various 
Societies  represented  definite  information  concerning  the  properties  of  con- 
crete and  reinforced  concrete,  and  to  recommend  factors  and  formulae 
required  in  the  design  of  structures  in  which  this  material  is  used.  While 
the  Joint  Committee  has  thus  far  accomplished  little  toward  formulating  a 
report,  it  has,  nevertheless,  acquired  a  definite  knowledge  of  the  work  such 
a  report  demands. 

The  tests  made  prior  to  the  appointment  of  the  Committee  were 
scattered  and  somewhat  fragmentary,  and  while  yielding  information  of 
considerable  value,  the  limited  scope  of  the  work,  lack  of  uniformity  of 
conditions,  and  methods,  and  failure  to  properly  report  details  concerning 
tests  or  to  complete  the  investigations,  render  the  results  insufficient  for  the 
formulation  of  a  report.  The  Committee,  therefore,  decided  that  it  was 
desirable  to  conduct  tests  along  certain  lines.  Until  recently  the  only 
channels  open  to  the  Committee  for  conducting  such  investigations  were 
the  laboratories  of  the  technological  institutions  and,  perhaps,  a  few  others. 

At  the  meeting  of  the  Joint  Committee  held  during  the  international 
Engineering  Congress  at  the  World's  Fair,  St.  Louis,  in  October,  1904,  the 
Committee  on  Tests  was  instructed  to  inaugurate  investigations  at  such 
technological  institutions  and  other  laboratories  possessing  the  requisite 
facilities  as  would  undertake  the  work.  Accordingly,  during  the  last  school 
year,  tests  were  made  under  this  Committee's  direction  in  the  laboratories 
of  some  twelve  engineering  schools.  The  results  have  been  reported  to  the 
Committee  on  Tests,  and  the  compilation  is  nearly  ready  for  presentation  to 
the  Joint  Committee.  The  plan  adopted  bv  the  Joint  Committee  involve* 
direction  and  inspection  of  this  work  by  the  committee  on  Tests.  This  the 
[TO] 


REPORT  OF  THE  SUB-COMMITTEE  OX  TESTS 

Committee  was  unable  to  do  through  lack  of  funds  with  which  to  pay  the 
expenses  of  inspectors  and  other  assistants. 

It  might  also  be  stated  that  the  first  year's  work  would  naturally  be 
of  a  preliminary  nature,  which  would  serve  to  develop  essential  points  to 
be   observed  and   the   provisions   to  be   made   in   future   tests.      Naturally, 
the  conditions  under  which  these  tests  were  made,  and  the  personal  equa- 
tions of  those  making  the  test  pieces,  and  the  ideas  of  those  supervising  the 
tests,  were  widely  at  variance,  and  the  results,  while  possessing  value,  ar 
not  fully  comparable  and  must  be  studied  individually. 
,      About  March  of  the  present  year  a  small  appropriation  was  made  to 
the   United   States   Geological   Survey   for  the   investigation   of   structural 
materials. 

In  the  determination  of  the  manner  in  which  this  money  should  be 
expended  it  was  deemed  advisable  to  create  for  the  purpose  a  National 
Advisory  Board  on  Fuels  and  Structural  Materials.  A  number  of  the 
members  of  the  Joint  Committee  were  appointed  members  of  this  Advisory 
Board,  and  through  their  influence  the  money  was  devoted  to  the  investi- 
gation of  cement  mortars  and  concretes. 

At  the  meeting  of  the  Joint  Committee  in  Cleveland,  on  June  21,  1905, 
it  was  decided  to  co-operate  with  the  United  States  Geological  Survey,  and 
the  Committee's  representatives  on  the  Government  Advisory  Board  were 
requested  to  advise  as  to  the  plan  for  this  cooperation. 

At  the  meeting  of  the  Committee  held  at  Atlantic  City,  on  June  30, 
1905,  a  formal  plan  of  cooperation  was  adopted  by  which  the  program 
of  the  Committee  on  Tests  was  to  be  carried  out  in  the  Government  labora- 
tories. These  laboratories,  known  as  the  "Structural  Materials  Testing 
Laboratories,"  have  been  organized  and  are  under  the  direction  and  super- 
vision of  the  present  Chairman  of  the  Committee  on  Tests.  It  was  also 
decided  to  conduct  the  investigations  at  such  institutions  as  the  Committee 
on  Tests  might  elect,  under  the  direction  of  the  Committee  and  the  inspec- 
tion of  the  representative  of  the  Government  laboratories.  Accordingly,  ar- 
rangements have  been  made  for  carrying  on  tests  at  the  Universities  of  Illi- 
.  nois,  Purdue  and  Wisconsin  and,  possibly  Columbia.  These  tests  consist  of 
determinations  of  the  effect,  at  different  ages,  of  varying  percentages  of 
round,  square  and  flat  bars  of  steel  of  different  elastic  limit,  using  the  same 
concrete;  of  the  bond  under  similar  conditions;  of  the  properties'  of  tee- 
beams  ;  of  the  effect  of  loading  beams  centrally,  and  at  2,  4  and  8  points  : 
of  the  shearing  strength  of  concrete;  of  the  tensile  strength  and  modulus 
of  elasticity  of  concrete  in  tension  in  length  of  12  feet;  of  the  effect  of 
different  methods  of  reinforcing  a  beam  for  diagonal  tension. 

Policy  of  Committee 

The  policy  of  the  Joint  Committee,  up  to  the  present  time,  has  lacked 
definiteness.  It  is  evident  that,  to  secure  efficiency  the  Committee  must 
adopt  a  policy  to  govern  its  future  work. 


REINFORCED  CONCRETE 

It  is  apparent  that  it  would  be  desirable  to  conduct  a  comprehensive 
series  of  experiments  in  one  laboratory  where  the  conditions,  methods  and 
personal  equations  of  those  making  the  test  pieces  and  the  ideas  of  those 
supervising  the  tests  are  more  nearly  constant.  Thus  comparable  results 
would  be  obtained,  giving  the  uniformity  and  consistency  necessary  for 
the  development  of  essential  underlying  principles,  and  which  could  not  be 
expected  under  the  conditions  prevailing  at  different  places  and  under  the 
guidance  of  different  persons,  as  would  be  the  case  at  different  technological 
institutions. 

The  Committee  would,  by  this  means,  obtain  ultimately,  as  a  basis  for 
its  report,  a  complete  and  thorough  series  of  tests  made  by  the  same  squa< 
of  experienced  observers  acting  under  the  direct  supervision  of  those 
having  both  the  ability  to  judge  of  the  thoroughness  and  reliability  of  tin 
work  and  the  necessary  time  to  devote  to  its  supervision. 

The  wide  area  over  which  the  technical  schools  are  scattered  renders 
the  expense  of  providing  uniform  materials  and  of  inspecting  the  prepara 
tion  of  the  test  pieces  and  the  execution  of  tests  very  great.  Besides,  the 
work  cannot  generally  be  carried  on  uniformly  throughout  the  year,  but 
must  be  concentrated  into  a  few  months.  This  is  a  serious  difficulty  in  any 
series  of  tests. 

However,  in  the  progress  of  these  investigations,  there  will  necessarily 
be  considerable  experimental  work  in  opening  up  certain  phases  of  a  prob- 
lem, as,  for  example,  the  study  of  proper  methods  to  be  followed,  sources  of 
error  to  be  guarded  against,  the  probable  cause  of  a  given  phenomenon, 
that  would  be  of  material  help  in  planning  the  work,  or  in  corroborating 
the  results  of  other  tests ;  and  it  would  seem  wise  to  secure  the  cooperation 
of  the  technical  schools,  utilizing  their  faculties  to  the  extent  indicated,  in 
carrying  on  investigations. 

The  entire  Joint  Committee  has  been  divided  into  a  number  of  sub- 
committees for  the  purpose  of  collating  existing  literature  and  the  result 
of  previous  investigations.     These  results,  when  compiled,  will  serve,  wit" 
the   recommendation   of  each   Committee,   as   a   guide   in   formulating  the 
future  work  of  the  Joint  Committee.     The  results  of  the  compilations  oi 
the  various  sub-committees  shall  be  turned  over  to  the  Committee  on  Tests 
for  their  consideration  and  to  be  reported  by  them  to  the  Joint  Committee 
If  it  is  found  that  there  is  a  reasonable  concordance  in  certain  lines,   i 
would  seem  undesirable  for  the  Committee  on  Tests  to  plan  more  than  a  few 
confirmatory  experiments.     In  those  lines  where  there  is  no  agreement,  the 
Committee  work  must  necessarily  be  more  extensive  in  order  to  be  con- 
clusive. 

The  following  is  a  suggested  program  of  the  investigations  to  be  made 
by  the  Joint  Committee,  from  which  a  schedule  is  to  be  prepared  as  the 
tests  progress: 

[12]" 


REPORT  OF  THE  SUB-COMMITTEE  OX  TESTS 

Proposed  Program  for  the  investigation  of  Concrete  and  Reinforced 

Concrete* 

I.     Examination  and  Classification  of  Constituent  Materials: 
Sands,  gravels,  stones,  gravel  and  stone  screenings  (^4 -inch  screen),  slags 
cinders,  etc.,  to  be  collected  by  a  special  representative  of  the  Testing  Labora- 
tory sent  out  for  that  purpose. 

A.  EXAMINATION   OF   DEPOSIT 

as  to  the  extent  and  nature  of  the  material  from  which  the  samples 
are  collected. 

B.  PHYSICAL   TESTS   IN    THE   LABORATORY  I  .... 

1.  Mineralogical  examination, 

2.  Specific  gravity, 

3.  Weight  per  cubic   foot, 

4.  Sifting  (granularmetric  composition), 

5.  Percentage  of  silt  and  character  of  same, 

6.  Percentage  of  voids, 

7.  Character  of  stone  as  to  percentage  of  absorption,  porosity, 
permeability,  compressive  strength  and  behavior  under  treat- 
ment. 

C.  CHEMICAL    ANALYSIS 

as  to  the  character  of  the  stone,  silt,  etc.,  used  in  tests. 

//.      Tests  and  Classification  of  Mortars: 

made  with  Typical  Portland  Cement  and  sand,  gravel  and  stone  screenings 
(^-inch  screen).     Proportions  to  be  stated  by  weight  and  volume.     Unit 
of  volume  for  cement,  100  Ibs.  per  cubic  foot.    The  typical  Portland  cement 
to  be  prepared  by  thoroughly  mixing  a  number  of  brands,  each  of  which 
must  meet  the  following  requirements: 
Specific  gravity,  not  less  than  3.10. 
Fineness,  residue  not  more  than  8%  on  No.  100  or  25%  on  No  200 

sieve. 
Time  of  setting: 

Initial  set,  not  less  than  30  minutes; 
Hard  set,  not  less  than  i  hour  or  more  than  10  hours. 
Tensile  strength : 
Neat, 

24  hours  in  moist  air,  I75lbs. 

7  days  (i  day  in  moist  air,  6  days  in  water)          5oolbs 

28  days  (iday  in  moist  air,  27  days  in  water)       6oolbs. 

^Approved  by  National  Advisory  Board  on  Fuels  and  Structural  Materials  at  the  meet- 
ing held  at  Washington,  D.  C.,  March  3ist,  1906. 
One  part  cement,  3  parts  standard  sand : 

7  days   (i   day  in  moist  air,     6  days  in  water)      I75lbs. 
28  days   (i   day  in  moist  air,  27  days  in  water)     25olbs. 

[13] 


REINFORCED  CONCRETE 

Constancy  of  volume  : 

Pats  of  neat  cement  3  inches  in  diameter,  j/2-inch  thick  at  center, 
tapering  to  a  thin  edge,  shall  be  kept  in  moist  air  for  a  period 
of  24  hours : 

A.  A   pat   is   kept   in   air   at  normal   temperature   and   observed   at 
intervals  for  at  least  28  days. 

B.  Another  pat  is  kept  in  water  maintained  as  near  70  deg.   F.  as 
practicable  and  observed  at  intervals  for  at  least  28  days. 

c.     A  third  pat  is  exposed  in  an  atmosphere  of  steam  above  boiling 
water  in  a  loosely  closed  vessel  for  5  hours. 

These  pats  must  remain  firm  and  hard  and  show  no  signs  of  distor- 
tion, checking,  cracking  or  disfiguration. 

The  cement  shall  not  contain  more  than  1.7$%  Anhydrous  sulphuric 
acid   or   more   than   4%    magnesium   oxide. 

A  test  of  the  neat  cement  must  be  made  with  each  mortar  series  for 
for  comparison  of  the  quality  of  the  typical    Portland  cement. 

A.       PHYSICAL   TKSTS    IN    LABORATORY  : 

1.  Tensile  strength  with  one  part  cement  to  varying  percentages 

of  material  under  test,  for  7,  28,  90,  180  and  360  days ; 

2.  Compressive  strength  with  one  part  cement  to  varying  percent- 

ages of  material  under  test,  for  7,  28,  90,  180  and  360' days; 

3.  Transverse  strength  with  one  part  cement  to  varying  percent- 

ages of  material  under  test,  for  7,  28,  90,  180  and  360  days; 

4.  Shearing  strength  with  one  part  cement  to  varying  percent- 

ages of  material  under  test,  for  7,  28,  90,  180  and  360  days ; 

5.  Tensile  strength  with  cement,  material  sieved  to  one  size,  for 

7,  28,  90,  180  and  360  days; 

6.  Compressive  strength  with  cement,  material  sieved  to  one  size, 

for  7,  28,  90,  180  and  360  days; 

7.  Transverse  strength  with  cement,  material  sieved  to  one  size, 

for  7,  28,  90,  1 80  and  360  days ; 

8.  Shearing  strength   with  cement,   material   sieved   to  one   size, 

for  7,  28,  90,  1 80  and  360  days ; 

9.  Modulus  of  elasticity  in  compression  of  different  mixtures  as 

to  proportion  and  size  of  the  aggregate,  for  30.  90,  180  and 
360  days ; 

[14] 


.REPORT  OF  THE  SUB-COMMITTEE  O\  TESTS 

10.  Modulus  of  elasticity  in  tension  of  different  mixtures  as  to 
proportion  and  size  of  aggregate,  for  30,  90,   180  and  360 
days ; 

11.  Yield  in  mortar; 

12.  Porosity; 

13.  Permeability; 

14.  Volumetric  changes  in  setting ; 

15.  Absorption; 

16.  Methods   of  waterproofing; 

17.  Freezing  tests; 

1 8.  Coefficient  of  expansion ; 

19.  Effect  of  oil: 

(a)  On  hardening  mortar, 

(b)  On  hardened  mortar; 

20.  Effect  of  sea  water. 

///.      Tests  and  Classification  of  Concrete: 

made  with  typical  Portland  cement  and  sand,  gravel  and  stone  screenings 
ings,  gravel,  sand,  cinder,  slags,  etc.  Proportions  to  be  stated  by  weight 
and  volume.  Unit  of  volume  for  cement,  100  Ibs.  per  cubic  foot. 

A.       PHYSICAL  TESTS   IN   LABORATORY  : 

1.  Tensile   strength   with    different   mixtures    as   to    proportion 

and  size  of  the  aggregate,  for  30,  90,  180  and  360  days ; 

2.  Compressive  strength  of  different  mixtures  as  to  proportion 
and  size  of  the  aggregate,  for  30,  90,  180  and  360  days; 

3.  Transverse  strength  of  different  mixtures  as  to  proportion 

and  size  of  the  aggregate,  for  30,  90,  180  and  360  days; 

4.  Shearing  strength  with  different  mixtures  as  to  proportion 
and  size  of  the  aggregate,  for  30,  90,  180  and  360  days; 

5.  Modulus  of  elasticity  in  compression  of  different  mixtures  as 

to  proportion  and  size  of  aggregate,  for  30,  90,  180  and  360 
days; 

6.  Modulus    of   elasticity    in    tension    of    different    mixture    as 

to  proportion  and  size  of  aggregate,  for  30.  90,  180  and  360 
days ; 

7.  Character  crushed  stone  used : 

(a)   Weight  per  cubic  foot, 
•    (b)   Size, 

(c)  Percentage  of  voids, 
fd)   Percentage  of  silt: 

8.  Weight  per  cubic  foot,  uncrushed : 

9.  Yield ; 

10.  Absorption ; 

11.  Porosity; 

12.  Permeability; 

[15] 


REINFORCED  CONCRETE 

13.  Methods  of  waterproofing; 

14.  Protective  influence  against  corrosion  of  metal; 

15.  Fire  resisting  qualities: 

(a)  Effect  of  heat  on  hardening  concrete, 

(b)  Effect  of  heat  on  hardened  concrete, 

(c)  Thickness  necessary  for  proper  insulation. 

1 6.  Freezing  tests ; 

17.  Volumetric  changes; 

18.  Effect  of  vibration  and  of  applied  stress  (impact)  ; 

(a)  On  a  hardening  of  a  plain  and  reinforced  concrete, 

(b)  On  hardened  plain  and  reinforced  concrete; 

19.  Adhesion  of  concrete  to  metal  under  varying  conditions,  for 
varying  periods,  up  to  at  least  three  years : : 

(a)  Effect  of  shape, 

(b)  Effect  of  embedded  length, 

(c)  Effect  of  various  kinds  of  loading, 

(d)  Effect  of   chemical   action, 

(e)  Relative  value  of  surface  adhesive  resistance  and  grip; 

20.  Effect  of  oils: 

(a)  On  hardening  concrete, 

(b)  On  hardened  concrete; 

21.  Coefficient  of  expansion; 

22.  Effect  of  sea  water. 

B.     FULL  SIZE  TESTS: 

1.  Beams  of  various  spans,  sections  and  compositions; 

2.  Building  blocks  and  bricks,  as  to: 

(a)  Compressive  strength,  wet  and  dry  mixtures, 

(b)  Transverse  strength,  wet  and  dry  mixtures, 

(c)  Shearing  strength,  wet  and  dry  mixtures, 

(d)  Absorption,  wet  and  dry  mixtures, 

(e)  Permeability, 

(f)  Methods  of  Waterproofing, 

(g)  Effect    of    accelerating    the    hardening    of    concrete 

blocks  by  means  of  live  steam,  etc., 
(h)   Fire  resisting  qualities, 
(i)   EfHorescence. 

IV.      Tests  of  Reinforced  Concrete: 

A.       BEAMS  : 

1.  Effect  of  amount  of  reinforcement, 

2.  Effect  of  character  of  reinforcement, 

3.  Effect  of  form,  size,  and  position  of  reinforcing  bars, 

4.  Effect  of  initial  stress  in  reinforcement, 

5.  Effect  of  different  manners  of  loading, 

6.  Methods  of  providing  for  diagonal  stresses, 

[16] 


REPORT  OF  THE  SUB-COMMITTEE  O\  TESTS 

7.  Effect  of  variation  in  section,  such  as  trapezoidal,  tee-shaped, 

etc., 

8.  Effect  of  variation  in  length  and  depth, 

9.  Effect  of  restraining  the  ends, 
10.     Effect  of  repetitive  loading. 

B.     COLUMNS: 

1.  Effect  of  amount  of  reinforcement, 

2.  Effect  of  disposition  of  reinforcement : 

(a)  Longitudinal, 

(b)  Hooped, 

(c)  Combination  of  (a)  and  (b), 

3.  Effect  of  form,  size,  and  position  of  reinforcement, 
.  4.     Effect  of  character  and  eccentricity  of  loading, 

5.  Effect   of   variation   in   section,    such   as    square,    round   and 

rectangular, 

6.  Effect  of  fixing  the  ends, 
c.     SLABS  : 

1.  Supported  at  two  or  four  edges, 

2.  Eixed  at  two  or  four  edges, 

3.  Use  of  expanded  metal,  wires,  etc., 

4.  Effect  of  concentration  of  load, 

5.  Variation  in  per  cent,  of  reinforcement, 

6.  Variation  in  span  and  thickness. 
D.     ARCHES  : 

1.  Continuous  ring, 

2.  Hinged, 

3.  Voussoirs, 
4  Shape, 

5.     Span  and  rise. 

As  regards  the  work  in  the  technological  institutions,  it  is  recommended 
that  there  be  taken  up,  in  a  limited  number  of  schools  possessing  the  proper 
facilities,  investigations  comprising,  in  part,  tests  in  which  the  methods  of 
execution  are  still  open  to  formulation  and  which  involve  general  phe- 
nomena. In  addition  to  this,  it  is  recommended  that  the  Committee  on  Tests 
be  authorized  to  offer  its  services  in  an  advisory  capacity  to  any  laboratory 
conducting  investigations  of  this  character.  The  following  list  is  suggested 
as  available  at  present : 

1.  Shearing, — Comparison   of  methods; 

2.  Modulus  of  elasticity, — Comparison   of  methods ; 

3.  Protective  influence  of  concrete  against  corrosion ; 

4.  Fire  resisting  qualities  of  concrete; 

5.  Methods  of  waterproofing; 

6.  Coefficient  of  expansion  ; 

7.  Effect  of  vibration  and  applied  stress ; 

8.  Adhesion  of  concrete  to  metal ; 

[17] 


REINFORCED  CONCRETE 

9.  Reinforced  concrete  beams : 

(a)  Effect  of  different  manners  of  loading, 

(b)  Methods  of  providing  for  diagonal  stresses, 

(c)  Effect  of  variation  in  section, 

(d)  Effect  of  restraining  ends, 

(e)  Amount  and  character  of  reinforcement; 
10.     Reinforced  concrete  columns, — Method  of  testing. 

The  direction  of  all  this  work  is  to  be  under  the  Committee  on  Tests, 
as  provided  in  the  rules  of  organization. 

Summary  of  Recommendations 

The  foiling  is  a  summary  of  recommendations: 

1.  A  comprehensive  series  of  tests  to  be  conducted  under  the 

direction  of  the  Committee  on  Tests  at  some  point  in 
in  cooperation  with  the  United  States  Geological  Survey. 

2.  The  cooperation  of  the  technological  schools  in  tentative  or 

general  experimental  work  under  the  direction  of  the 
Committee  on  Tests. 

3.  The  collation  of  existing  literature  and  results  of  previous 

experiments  by  sub-committees  of  the  Joint  Committee, 
to  be  reported  to  the  Committee  on  Tests  for  its  con- 
sideration, and  to  be  reported  by  them  to  the  Joint 
Committee. 

The  Committee  on  Tests  has  endeavored  to  outline  a  definite  policy 
from  which  it  may  reasonably  expected  to  derive  the  requisite  data  for  the 
formulation  of  its  final  report. 

Each  member  of  the  Joint  Committee  should  be  willing  to  render  all 
possible  assistance  in  carrying  out  the  program,  and  the  Committee  on 
Tests  would  further  emphasize  the  fact  that,  unless  the  Joint  Committee 
takes  hold  of  the  work  in  a  vigorous  manner  and  provides  ample  funds 
for  the  purpose,  the  Joint  Committee  had  better  be  disbanded. 

The   Committee   on    Tests    cannot   emphasize   too    strongly   the    vital 
importance  to  the  engineering  profession  of  the  results  to  be  derived  if  the 
program  proposed  be  carried  out  in  an  efficient  manner. 
Submitted  by  the  Committee  on  Tests. 

RICHARD  L.  HUMPHREY, 

Chairman. 
Committee  on  Tests, 

RICHARD  L.  HUMPHREY,    . 
A.  N.  TALBOT, 
W.  K.  HATT, 
OLAF  HOFF, 
GEORGE  F.  SWAIN, 
SPENCER  B.  NEWBERRY. 

[18]. 


UNITED     STATES     ADVIS- 
ORY BOARD   ON  FUEL 
AND  STRUCTURAL 
MATERIALS 

( United  States  Geological  Survey) 

The  Structural  Materials  Testing  Laboratories   In- 
vestigation of  Mortar  and  Concrete 
Building  Blocks 

I      Variables  entering  in   the  manufacture  of  blocks  under 
investigation. 

A.     Type  of  Wall  Block — all  plain  face  and  standard  ends. 
(i)   With  facing 

(a)   One  piece  Wall  Block, 
i.     Hollow  block. 

(a)  Down  face. 

(x)    Single  air  space, 
(y)   Double  air  space, 

(b)  Side  face, 

(x)   Single  air  space, 
(y)   Double  air  space, 
2.     Solid  block, 

(a)  Down  face. 

(b)  Side  face. 

(b)   Two  piece  wall  block. 

(a)  With  metallic  Bond. 

(b)  Without  metallic  Bond. 
(2)     Without  facing. 

(a)   One  piece  wall  block. 
T.     Hollow   Block 

(a)  Down  face. 

(x)    Single  air  space, 
(y)   Double  air  space, 

(b)  Side  face. 

(x)    Single  air  space, 
(y)   Double  air  space. 


!\>  111  \FORCED  CONCRETE 

•*°c*«  '2.*  '  Solid  btocfc/* . 

(a)  Down  face, 

(b)  Side  face, 

(b)   Two  piece  wall  black  solid  face. 

(a)  With  metallic  bond. 

(b)  With  metallic  bond. 

B.     Materials  Used. 

1.  Cement. 

Typical  Portland. 

2.  Aggregate. 

(a)  Single. 

1.  Sand. 

2.  Limestone. 

3.  Granite. 

4.  Gravel. 

5.  Cinder. 

(b)  Double,  consisting  of  sand  and 

1.  Limestone. 

2.  Granite, 

3.  Gravel. 

4.  Cinder. 

c.     Dimensions  of  Specimen. 

1.  Outside. 

(a)  8  x  8  x  16. 

(b)  9  x  12  x  24. 

2.  Web—  iy2"  to  3". 

3.  Air  space— 30  to  33  1-3%. 

D.  Consistency. 

1.  Damp. 

2.  Medium. 

3.  Wet. 

E.  Proportions. 

1.  Mortar. 

(a)  1:2, 

(b)  1:4, 

(c)  1:8, 

(d)  Balanced  proportions  for  waterproofing. 

2.  Concrete. 

(a)  1:1:3. 

(b)  1:2:4. 

(c)  1:3:6. 

(d)  Balanced  proportions   for  waterproofing. 

[20] 


U.  S.  ADVISORY  BOARD  ON  FUEL 

F.  Process  of  Manufacturing. 

1.  Mising. 

(a)  Hand. 

(b)  Machine. 

2.  Molding. 

(a)   Wet  mixture — cast  in  molds    in    which     test     pieces 

remain  until  hard  set. 
(i.)     Sand  Molds. 

(a)  Poured  without  vibration, 

(b)  Poured  witht  vibration. 
(2.)     Metal  molds. 

(a)  Poured  without  vibration. 

(b)  Poured  with  vibration. 

(b)     Damp  and     medium  mixtures — cast  in  molds  from  which 
specimens  are  removed  before  hard  set. 

1.  Hand  tamped. 

2.  Power  tamped. 

(a)  Air. 

(b)  Mechanical. 

1.  Single  application. 

2.  Repeated  application. 

G.  Curing. 

1.  Natural. 

(a)  Air. 

(b)  Air  and  sprinkling. 

2.  Artificial. 

(a)  Submerging. 

(b)  Steam. 

1.  Low  pressure. 

(a)  With  CO2. 

(b)  Without  CO2. 

2.  High  pressure. 

(a)  With  CA2. 

(b)  Without  CA2. 
H.     Aging. 

1.  Blocks  that  are  fired  60  days. 

2.  Blocks  that  are  not  fired. 

(a)  4  weeks. 

(b)  13  weeks. 

(c)  26  weeks. 

(d)  52  weeks. 

j.     Use  of  waterproofing  compounds, 
i.     Applied  to  surface. 


REINFORCED  CONCRETE 

2.     Added  to  material. 

(a)  Body. 

(b)  Facing. 

II      Properties  to  be  investigated. 

A.     Strength. 

I.     Transverse. 

(a)  Type. 

(b)  Material  used. 

(c)  Dimensions  of  specimens. 

(d)  Consistency. 

(e)  Proportions. 

(f)  Process  of  manufacturing. 

(g)  Curing, 
(h)  Aging. 

(j)   Use  of  waterproofing  compound?. 

2  Compression. 

(a)  Type. 

(b)  Material  used. 

(c)  Dimensions  of  specimens. 

(d)  Consistency. 

(e)  Proportions. 

Cf)    Process  of  manufacturing. 

(g)   Curing. 

(h)  Aging. 

(j)   Use  of  waterproofing  compounds. 

3  Shearing. 

(a)  Type. 

(b)  Material  used. 

(c)  Dimensions  of  specimens. 

(d)  Consistency. 

(e)  Proportions. 

(f)  Process  of  manufacturing. 

(g)  Curing, 
(h)  Aging. 

(j)   Use  of  waterproofing  compounds. 

B.     Permeability. 

(a)  Type, 
(i)     Block. 

(2)     Special  test  piece. 

(b)  Material  used. 

(c)  Dimensions  of  specimens. 

(d)  Consistency. 

[22] 


U.  S.  ADVISORY  BOARD  ON  FUEL 

(e)  Proportions. 

(f)  Process  of  manufacturing. 

(g)  Curing, 
(h)  Aging. 

(j)   Use  of  waterproofing  compounds, 
c.     Absorption. 

(a)  Type. 

(b)  Material  used. 

(c)  Dimensions  of  specimens. 

(d)  Consistency. 

(e)  Proportions. 

(f)  Process  of  manufacturing. 

(g)  Curing. 

(j)   Use  of  waterproofing  compounds. 

D.  Efflorescence. 

(a)  Type. 

(b)  Material  used. 

(c)  Dimensions  of  specimens. 

(e)  Proportions. 

(f)  Process  of  manufacturing. 

(g)  Curing, 
(h)  Aging. 

(j)  Use  of  waterproofing  compounds. 

E.  Fire  resisting  properties. 

(  i  )      Fired  and  Cooled  in  Air. 

(a)  Type. 

(b)  Material  used. 

(c)  Dimensions  of  specimens. 

(d)  Consistency. 

(e)  Proportions. 

(f)  Process  of  manufacturing. 

(g)  Curing, 
(h)   Aging. 

(j)   Use  of  waterproofing  compounds. 
(2)      Fired  and  cooled  by  spraying  with  water. 

(a)  Type. 

(b)  Material  used. 

(c)  Dimensions  of  specimens. 

(d)  Consistency. 

(e)  Proportions. 

(f)  Process  of  manufacturing. 

(g)  Curing, 
(h)  Aging. 

(j)   Use  of  waterproofing. 

[23] 


REINFORCED  CONCRETE 

List  of  Members  National  Advisory  Board  on  Fuel  and  Struc- 
tural Materials. 

From  the  American  Institute  of  Mining  Engineers: 

John  Hays   Hammond,   Past-President,  Empire   Building,   New   York. 

Robert  W.  Hunt  (of  Robert  W.  Hunt  &  Co.,  Testing  Engineers,  Chi- 
cago, Pittsburg,  and  New  York),  Chicago,  111.; 

B.  F.  Bush,  Manager  and  Vice-President,  Western  Coal  and  Mining 
Co.,  St.  Louis,  Mo. 

From  the  American  Institute  of  Electrical  Engineers : 

versity,  New  York ; 

Henry  C.  Scott,  Superintendent  Motive  Power,  Interborough  Rapid 
Transit  Co.,  New  York. 

From  the  American  Society  of  Civil  Engineers : 

C  .C.  Schneider,  President,  Chairman  Committee  on  Concrete  and  Rein- 
forced Concrete,  Pennsylvania  Building,  Philadelphia,,  Pa. ; 

George  S.  Webster,  Chairman  Committee  on  Cement  Specifications,  City 
Engineer,  City  Hall,  Philadelphia,  Pa. 

From  theAmerican  Society  of  Mechanical  Engineers : 

W.  F.  M.  Gross,  Dean  of  the  School  of  Engineering,  Purdue  Uni- 
versity, Lafayette,  Indiana. ; 

Geoige  H.  Barrus,  Steam  Engineer,  Pemberton  Square,  Boston,  Mass.; 
P.  W.  Gates,  210  State  Street,  Chicago,  111. 

From  the  American  Society  for  Testing  Materials : 
Charles  B.  Dudley,  President,  Altoona,  Pa. ; 

Robert  W.  Lesley,  Vice-President,  Pennsylvania  Building,  Philadel- 
phia, Pa. 

From  the  American  Institute  of  Architects : 

George  B.  Post,  Past-President,  33  East  Seventeenth  Street,  New  York. ; 
William  S.  Fames,  Past-President,  Lincoln  Trust  Building,  St.  Louis, 
Mo. 

From  the  American  Railway  Engineering  and  Maintenance  of  Way  Asso- 
ciation : 

H.  C.    Kelley,  President,  Minneapolis,  Minn. ; 

Julius  Kruttschnitt,  Director  of  Maintenance  and  Operation,  Union  Pa- 
cific Railway,  135  Adams  Street,  Chicago,  111.; 

Hunter  McDonald,    Past-President,   Chief   Engineer,   Nashville,    Chat- 
tanooga &  St.  Louis  Railway,  Nashville,  Tenn. 
[24] 


U.  S.  ADVISORY  BOARD  OX  FUEL 

From  the  American  Railway  Master  Mechanics'  Association: 

J.  F.  Deems,  General  Superintendent  of  Motive  Power,  New  York  Cen- 
tral Lines,  New  York ; 

A.  W.  Gibbs,  General  Superintendent  of  Motive  Power,  Pennsylvania 
Railroad,  Altoona,  Pa. 

From  the  American  Foundrymen's  Association : 

Richard  Holdenke,  Secretary,  Watchung,  N.  J. 
From  the  Association  of  American  Portland  Cement  Manufacturers : 

John  B.  Lober,  President,  Land  Title  Building,  Philadelphia,  Pa. 
From  the  Geological  Society  of  America : 

Samuel  Calvin,  Professor  of  Geology,  University  of  Iowa,  Iowra  City, 
Iowa. ; 

I.  C.  White,  State  Geologist,  Morgantown,  W.  Va. 

From  the  Iron  and  Steel  Institute : 

Julian  Kennedy,  Metallurgical  Engineer,  Pittsburg,  Pa. : 
C.  S.  Robinson,  General  Manager,  Colorado  Fuel  £  Iron  Co.,  Denver, 
Colo. 

From  the  National  Association  of  Cement  Users : 

Richard  L  Humphrey,  President,  St.  Louis,  Mo. 
From  the  National  Board  of  Fire  Underwriters: 

Chas.   A.   Hexamer,   Chairman,   Board  of  Consulting  Experts,    Bullitt 
Building,  Philadelphia,  Pa. 

From  the  National  Brick  Manufacturers'  Association: 

John  W.  Sibley,  Treasurer,  Sibley-Menge  Press  Brick  Co.,  Birmingham, 

Ala. ; 
Wm.  D.  Gates,  American  Terra  Cotta  &  Ceramic  Co.,  Chicago,  111. 

From  the  National  Fire  Protective  Association : 

O.  U.  Crosby,  Chairman  Executive  Committee,  76  William  Street,  New 

York. 
From  the  National  Lumber  Manufacturers'  Association : 

Nelson  W.  McLord,  President,  Equitable  Building,  St.  Louis,  Mo.; 
John  L.   Kaul,   President  Southern   Lumber  Manufacturers'     Associa- 
tion, Birmingham,  Ala. 

[25] 


REINFORCED  CONCRETE 

From  the  Corps  of  Engineers,  U.  S.  Army : 

Lieut.  Col.  Wm.  L.  Marshall,  Army  Building,  New  York. 
From  the  Isthmian  Canal  Commission : 

Lieut.  Col.  O.  H.  Ernst,  Washington,  D.  C. 

From  the  Bureau  of  Yards  and  Docks,  U.  S.  Navy : 

Civil  Engineer,  Frank  T.   Chambers,  Washington,  D.   C. 

From  the  Supervising  Architect's  Office,  U.  S.  Treasury  Department 
James  K.  Taylor,  Supervising  Architect,  Washington,  D.  C. 

From  the  Reclamation  Service,  U.  S.  Interior  Department: 
F.  H.  Xewell,  Chief  Engineer  Washington,    D.  C. 


[26] 


FRENCH  RULES  ON  REIN- 
FORCED CONCRETE 

A  complete   report    of  the   official    instructions  just 

issued  by  the  ministry  of  public  works  to  govern 

the  use  of  reinforced  concrete  in  France 

Translated  specially  by  CEMENT  AGE. 
Copyright,  1996,  by  Robert  W.  Lesley,  Phila. 

We  present  herewith  a  specially  prepared  translation  of  the  important 
Instructions,  /.  f.  Rules  on  Reinforced  Concrete  issued  by  the  French  Min- 
istry of  Public  Works,  together  with  an  explanatory  circular  of  the  highest 
possible  interest. 

Without  in  any  way,  at  this  stage,  commenting  upon  either  the  Rules 
or  the  Circular,  we  would  emphasize  what  is  indicated  below,  that  this  pub- 
lication is  based  upon  the  work  of  a  special  commission  of  some  five  years' 
standing,  and  upon  the  elaborate  investigations  conducted  at  the  instance  of 
that  commission. 

If  the  Rules  and  the  Circular  do  not  in  every  zvay  suit  the  conditions 
of  design  and  workmanship  beyond  the  borders  of  France,  and  thus  cannot 
serve  as  a  universal  model,  they  nevertheless  can  serve  as  a  skeleton  upon 
which  to  base  future  requirements. 

As  to  our  translation,  it  has  been  prepared  by  a  French  civil  engineer 
of  high  standing,  and  revised  by  one  of  our  most  valued  contributors,  and 
if  it  lacks  perfection  it  will  not  be  for  the  want  of  care.  To  would-be  users 
of  this  translation,  we  should  perhaps  sound  a  note  of  warning  that  we  are 
protected  by  copyright  (including  the  English  copyright}  but  shall  be 
happy  to  meet,  as  far  as  possible,  any  requests  of  would-be  users,  who  may 
apply  to  us  in  writing  for  permission. 

THE    popularity    of    reinforced    concrete    for    structural    work    in 
France   caused   the    French   Government,   as    far   back  as    1901, 
to    recognize   the    necessity   of   issuing    data    for   the    guidance 
of    building      owners   generally   and    their   own   technical    staff 
in  particular. 

Thus  the  "Commission  du  Ciment  Arme"  came  to  be  appointed  in  1901 
by  the  Ministre  des  Travaux  Publics,  (Public  Works)  with  instructions  to 
make  enquiries  and  elaborate  administrative  rules  to  be  applied  in  official 
contracts* 

The  first  meetings  of  this  commission   were  held  in  March,   1901,  in 

*The  Commission  comprised  MM.  Lorieux,  Inspecteur-General  (chairman);  Re"zal 
Rabut,  Bechmann,  ConsideVe,  Harel  de  la  Noe,  Ingenieurs-en-Chef,  Professeurs  a 
1'Ecole  des  Fonts  et  Chausse*es;  Boitel,  Royel  Engineer  Officer;  Hartman,  Artillery 
Officer;  Gautier  and  Hermant,  Architects;  Mesnager,  Engineer;  Candlot,  Coignet  and 
Hennebique,  specialist  contractors. 

I  [271 


REINFORCED  CONCRETE 

order  to  determine  the  programe  of  the  research  work  to  be  carried  out. 
This  research  work  was  ordered  to  comprise  enquiries  as  to  the  mechanical 
behaviour  of  mortar  and  concrete,  with  or  without  reinforcements,  more 
particularly  as  to  the  laws  of  compressive,  tensile,  shearing,  slipping  and 
adhesive  stresses,  the  variations  of  volume  resulting  from  the  hardening  pro- 
cess and  from  climatic  changes ;  further,  the  influence  of  the  proportion  and 
of  the  qualities  of  ingredients,  the  relative  efficiency  of  various  arrange- 
ments for  reinforcements,  the  degree  of  water-tightness,  fire  resistance  and 
wear,  the  effect  of  shocks  and  any  reciprocal  assistance  received  from 
neighboring  pieces,  etc.  Further,  certain  tests  "to  destruction"  were 
ordered  upon  various  structures  in  reinforced  concrete  that  had  been  erected 
in  1901  for  the  Paris  International  Exhibition. 

Five  years  were  not  too  much  for  such  experimental  research  work  and 
for  deducing  therefrom  accurate  data,  and  numerous  meetings  were  held  to 
formulate  the  results  obtained. 

The  conclusions  of  the  "Commission  du  Ciment  Arme"  were  finally 
submitted  to  the  Ministry  in  March,  1906,  which  department  then  referred  the 
matter  to  the  approbation  of  the  Conseil  General  des  Fonts  et  Chaussees, 
which  selected  three  of  its  membersf  with  the  examination  of  the  proposed 
rules.  This  Conseil  thoroughly  enquired  into  every  point;  called  upon 
the  leading  members  of  the  "Commission  du  Ciment  Arme"  to  personally 
argue  their  case,  and  hearing  with  deference  the  arguments  of  the  Com- 
mission's minority,*  who  had  so  strongly  advocated  a  separation  between 
the  Instructions,  i.  e.?  Rules,  and  the  Circulaire. 

The  actual  reason  why  the  Rules  are  officially  termed  "Instructions"  is 
we  believe,  due  to  their  being  considered  provisional. 

We  present  the  "Instructions"  (Rules)  in  full  translation  and  also  the 
explanatory  "Circular,"  which  affords  such  interesting  reading.  As  to  the 
"Instructions"  we  would,  however,  indicate  certain  features  in  summary  as 
follows : — 

The  limit  of  the  safe  stresses  allowed  in  designing  structures  in 

reinforced  concrete 

Compression. — Two  sevenths  of  the  crushing  strength  of  the  same 
concrete  experimented  without  reinforcements  on  a  cube  after  90 
days,  hardening.  This  rate  of  two-sevenths  may  be  increased  to 
three-fifths  if  the  longitudinal  and  transverse  reinforcements  are 
complying  with  certain  conditions. 

Shearing,  slipping  and  adhesion. — One-thirty-fifth  of  the  crushing 
strength  above  referred  to  for  plain  concrete. 

Tensile  and  compressive  reinforcements. — One-half  of  the  apparent 
limit  of  elasticity  to  be  specified  in  the  device  of  contraction  and 
five-twelfths  only  if  shocks  may  occur. 

tMaivrice  L,e"vy,    Inspecteur-General,     iere     Classe,     Membre     de     1'Institut;     de 
Preaudeau,  Vetillard,  Inspecteurs-Generaux  de  2eme  Classe. 

*  Which  comprised  MM.  Rabut  and  Mesnager: 

128]  : 


FREXCH  RULES  OX  REINFORCED  COXCRETE 

All  these  safe  stresses  are  to  be  decreased^  but  from  25  per  cent,  at 
most,  when  whatever  weakening  cause  may  be  forseen. 

Empirical  formulae  will  not  be  allowed,  but  only  scientific  ones. 

The  tensile  strength  of  concrete  is  to  be  considered  in  order  to  determine 
the  general  deformation;  but  for  computing  the  local  stresses  it  will  be  con- 
sidered as  nil. 

The  "Circulaire"  explains  that  the  ration  m  of  the  moduli  of  elasticity 
of  steel  and  of  concrete  was  found  experimentally  equal  to  10  by  Messrs. 
Rabut  and  Mesnager,  but  that  this  figure  would  not  be  justified  indifferently 
in  all  cases;  this  value  may  vary  from  8  to  15  to  be  inserted  in  the 
formulae  derived  from  the  elastic  theory,  according  to  the  diameter  of  the 
longitudinal  reinforcements  and  the  spacing  of  the  transverse  reinforce- 
ments in  ratio  of  the  least  dimension  of  the  piece. 

For  pieces  subjected  to  direct  compression  another  coefficient  m  is  to  be 
considered  besides  the  coefficient  m  amplifying  the  volume  of  the  longitud- 
inal reinforcements,  and  permitting  this  letter  to  be  summed  up  with  the 
volume  of  concrete  in  order  to  compute  the  total  sectional  area  of  a  fictive 
homogeneous  section  equalling,  from  a  mechanical  aspect,  the  heterogen- 
eous sectional  areas.  This  coefficient  m'  allows  the  amplification  of  the  total 
sectional  area  (fictitiously  homogeneous),  according  to  the  ratio  of  the 
volume  of  transverse  reinforcements  to  the  volume  of  concrete  and  their 
more  or  less  spacing. 

The  tenour  of  these  rules  is  to  induce  the  builders  to  use,  as  far  as  pos- 
sible, large  sections  of  ribs,  small  .diameters  of  reinforcements,  and  close- 
spaced  stirrups. 

COPYRIGHT. 

PROPOSED    INSTRUCTIONS     (Rules)     FOR     DESIGN 
OF    STRUCTURES    REINFORCED    CONCRETE. 

/.  —  Data  to  be  Allowed  i?i  Designing.  to  be  designed  with  regard  to  the  maximum 

A. — Loads  loads  which   such  structures  may  have  to 

1.  Bridges  in  reinforced  concrete  are  to       carry. 

be  designed  in  accordance  with  the  same  B.— Safe  Working  Stresses. 
vertical  loads  and  the  same  wind  pressures  4-    The   limit  of   compressive   stress   for 
as  those  required  by  the  Ministerial  regu-  reinforced  concrete  to  be  allowed  in  calcu- 
lations of  August  29th,  1891,  dealing  with  lations  shall  not  exceed  ^/^  of  the  crushing 
steel  girder  bridges  of  similar  types.  strength  of  plain  concrete  of  the  same  pro- 

2.  Roofs  in  reinforced  concrete  shall  be  portions  and  at  the  age  of  90  days.    The 
treated   from  the  point  of  view  of  loads  value  of  the  crushing  strength,  determined 
as  far  as  possible  in  accordance  with  the  by  tests   upon  8-in.   cubes  at   least,  to  be 
French  Ministerial  regulations  of  February  specified  in  every  contract. 

1 7th,  1903,  dealing  with  metallic  halls  for          5.    When  hooping,  transverse,  or  oblique 

railway  lines.  reinforcement    is    employed,    if    arranged 

3.  Floors  and  other  structural  features  suitably  to   resist  the  buckling  effect  due 
of  buildings,  retaining  walls,  tanks,  water  to    longitudinal    pressure,    the    safe    limit 
mains  under  pressure  and  any  construction  referred  to  in  Article  4  may  be  increased 
whatsoever  affecting  the  public  safety,  are  to  some  extent  in  proportion  to  the  volume 

[29] 


REINFORCED  CONCRETE 


of  reinforcing  bars,  and  to  their  more  or 
less  suitable  arrangement;  but,  whatever 
may  be  the  percentage  of  the  reinforcement 
employed,  the  limit  of  compressive  strength 
shall  not  exceed  3/5  of  the  crushing  strength 
of  plain  concrete  as  stated  in  Article  4. 

6.  The  safe  limit  for  shearing  and  slip- 
ping strains  in  the  concrete  in  respect  of  its 
own  fibres,  as  well  as  the  safe  limit  of  its 
adhesion  to  the  metal  used  as   reinforce- 
ment, may  be  taken  as  equal  to  Y™  of  the 
strength  specified  in  Article  4  for  the  safe 
limit  of  compressive  stresses. 

7.  The  safe  limit  of  tensile  as  well  as 
compressive  stresses  allowed  for  the  rein- 
forcement   shall   not    exceed    one-half    the 
value  of  the  elastic  limit  of  the  metal  em- 
ployed,   and   as    specified    in   the    contract. 
However,  for  members,  and  especially  for 
slabs     subject     to     alternating     shocks     or 
stresses,  this  limit  is  to  be  reduced  to  5/i2 
instead  of  one-half  the  elastic  limit. 

8.  For  members  subject  to  stresses  vary- 
ing within   wide   limits,   the   safe   working 
stresses  specified  above  are  to  be  reduced 
in  accordance  with  the  importance  of  such 
variations,  but  this  decrease  need  not  exceed 
25  per  cent. 

The  safe  limits  of  the  working  stresses 
are  to  be  reduced  also  for  members  subject 
to  weakening  causes  not  considered  in  the 
calculations,  particularly  to  dynamical 
action,  and  especially  for  members  directly 
supporting  railway  lines. 

//. — Calculations. 

9.  The   designer  of   structures   in   rein- 
forced concrete  has  to  take  into  account  not 
only  the  most  unfavourable  external  forces, 
including  the  weight  of  wind  and  snow,  but 
also  the  strains  resulting  from  changes  of 
temperature  and  those  due  to  the  expansion 
and  contraction  of  the  concrete  when  the 
structure  cannot  be  considered,  with  some 
certitude,  as  being  freely  dilatable,  theoreti- 
cally or  practically. 

10.  Calculations    are   to   be   based   upon 
scientific    methods    derived    from    experi- 
mental researches,  and  not  upon  empirical 
formulae;    the  calculations  may  be  deduced 
either    from   the  principles    of   the   elastic 
theory  or  from  principles  presenting  at  least 
an  equivalent  guarantee  of  exactitude. 

11.  The  tensile  strength  of  the  concrete 
shall  be  taken  into  account  when  calculating 

[30] 


deformation,  but  when  computing  the  local 
stresses  in  any  section,  the  tensile  strength 
of  the  material  is  to  be  considered  as  nil. 

12.  When  a  member  subjected  to  direct 
compression  is  free  over  a  length  exceeding 
18  diameters  (or  the  least  side),  it  is  neces- 
sary to  inquire  whether  it  is  liable  to  flexure. 

///. — Construction  of  Works. 

13.  The  moulds  and  centerings,  as  well 
as    the    disposition    of    the    reinforcement, 
must    afford    sufficient    rigidity    for    with- 
standing, without  noticeable  deflection,  the 
loads  and  shocks  occurring  during  construc- 
tion, including  those  caused  by  the  removal 
of  moulds  and  centerings. 

14.  Except   in   special   cases   where   con- 
crete is  poured,   the  cement  used  shall  be 
slow-setting,    and    the    concrete    carefully 
tamped   in    successive   layers,   whose   depth 
shall   be    suited   to   the   dimensions   of   the 
aggregate  and  to  the  spacing  of  the  rein- 
forcement;   this  depth  shall  not  exceed  2 
in.    after   tamping,   except   in   cases    where 
stones  are  employed  as  aggregate. 

15.  The   reinforcing   bars    are   to   be    so 
spaced  one   from  the   other  and   from  the 
sides  of  the  moulds,  that  perfect  ramming 
of  the  concrete  may  be  facilitated,  and  that 
the   concrete   may  be    forced   into   contact 
with  the  reinforcement.     The  thickness  of 
concrete  intended  to  protect  the  reinforce- 
ment against  changes  of  temperature  must 
be  at  least  3/4  in.,  even  in  cases  where  cement 
mortar  is  used  in  place  of  concrete. 

16.  When  special  sections  are  employed 
for   reinforcement   instead   of    round   bars, 
arrangements  must  be  made  to  provide  for 
the  perfect   encasing   of   the   bars   around 
their  entire  perimeter  and  particularly  at  all 
re-interring  angles. 

17.  When  the  construction  of  a  work  has 
been  stopped   (an  occurrence  that  shall  be 
avoided  as  far  as  possible),  the  concrete  is 
to  be  cleaned,  scraped  and  watered  for  a 
sufficient    time    to    moisten    it    thoroughly, 
before  fresh  concrete  is  deposited. 

18.  In  frosty  weather  the  work  must  be 
discontinued  if   efficacious  means   for  pre- 
venting the  prejudicial  effects  of  frost  are 
not  available.     In  resuming  the  work,  any 
part  of  the  concrete  which  may  have  been 
injured  is  to  be  cut  out.     In  other  respects, 
work  is  to  be  conducted  in  accordance  with 
Article    17. 


FRENCH  RULES  OX  REIXFORCED  CONCRETE 


19.  During  15  days,  at  least,  the  concrete 
must   be    kept    sufficiently   moist   to   insure 
its  setting  under  favourable  conditions. 

The  quality  and  proportions  of  the  in- 
gredients of  the  concrete  are  to  be  specified 
in  the  contract.  The  amount  of  water  used 
in  gauging  shall  be  supervised  accurately, 
and  must  be  sufficient  for  insuring  the 
fluidity  necessary  for  the  perfect  embedding 
of  the  reinforcement  and  the  complete  fill- 
ing of  all  voids  between  the  various 
ingredients  of  the  mixture. 

20.  The  moulds  and  centerings  are  to  be 
removed   without   any   shock ;    the   stresses 
developed  in  removing  them  must  be  merely 
static  and  the  set  of  the  concrete  ought  to 
be  sufficient  for  withstanding  such  stresses. 

IV.  —  Tests  of  the  Works. 

21.  Structures     in     reinforced     concrete 
affecting  the  public  security  must  be  tested 
before  use.     The  conditions  of  testing,  as 
well  as  the  limit  of  deflection  allowed,  are 
to  be  stated  in  the  general  specifications. 

The  age  of  the  works  tested  shall  be 
specified  also,  it  must  attain  at  least  90 
days  for  structures  of  primary  importance, 
45  days  for  ordinary  constructions,  and  30 
days  for  floors, 

22.  The  engineers*  shall  have,  in  testing, 
the  opportunity  not  only  of  observing  the 
deformations  and  of  verifying  other  speci- 
fied conditions,  but  also,  as  far  as  possible, 
of  making  scientific  investigations. 

23.  Bridges  in  reinforced  concrete  are  to 
be  tested  in  accordance  with  the  methods 
prescribed  by  the  Ministerial  regulations  of 
August  29th,  1891,  above  referred  to. 

Any  variations  from  those  regulations 
that  would  appear  suitable  in  any  particular 
cases  are  to  be  justified  and  specified  in  the 
contract. 

24.  Roofs  shall  be  tested  as  prescribed  in 
the    Ministerial    regulations    of    February 
I7th,    1903,    above    referred    to,    subject   to 
approved  variations. 

25.  Floors    shall    be    subjected    to    tests 
comprising  the  application  of  the  calculated 
permanent  and  moving  loads  acting  over 
the  whole  area  of  the  building,  or  at  least 
upon  entire  floor  panels. 

The  loads  are  to  be  left  in  position  for 

*  In  this  and  all  subsequent  cases  where  the  words 
the  engineers  are  used  they  refer  to  the  Ingemeurs 
des  Fonts  et  Chaussees.— En 


at  least  24  hours,  and  increase  of  deflection 
must  cease  after  15  hours. 

Proposed  Circular  Explaining  the  In- 
structions for  Design  of  Structures 
in  Reinforced  Concrete. 

Tn  consideration  of  the  extensive  develop- 
ment evidenced  in  reinforced  concrete  con- 
struction as  applied  to  public  works,  it  is 
necessary  to  call  the  attention  of  the  engi- 
neersf  to  the  general  conditions  under 
which  buildings  erected  in  this  new  material 
present  the  same  features  of  stability  and 
offer  the  same  guarantees  of  safety  to  the 
public  as  those  carried  out  in  materials  that 
have  been  in  use  for  a  long  time. 

Such  is  the  scope  of  these  Instructions. 
While  complying  with  the  actual  state  of 
our  knowledge  on  the  matter,  they  may 
probably  be  modified  when  the  experience 
derived  from  works  executed  or  from 
laboratory  experiments  and  from  the  longer 
use  of  reinforced  concrete  shall  have  fur- 
nished more  accurate  data  than  those  avail- 
able at  the  present  moment. 

The  object  of  the  following  explanations 
is  to  define  more  accurately,  so  far  as 
appears  necessary,  the  meaning  and  scope 
of  the  Instructions. 

/. — Data  to  be  Allowed  for  Designing. 

A. — Loads. 

Articles  i,  2  and  3.  The  two  first  articles 
require  no  comment.  The  third,  prescrib- 
ing that  the  structures  dealt  with  are  to  be 
designed  for  the  most  unfavourable  loads 
that  they  may  have  to  bear  when  in  use, 
appears  unnecessary,  as  every  work  must  be 
carried  out  and  thus  designed  in  view  of 
the  purpose  for  which  it  is  destined. 

That  is  true  for  metallic  structures  or 
any  other  class  of  building  construction  em- 
ployed before  the  introduction  of  reinforced 
concrete.  Such  buildings  are  designed  in 
view  of  supporting  with  a  suitable  factor  of 
safety  the  greatest  actual  loads  to  be  fore- 
seen, that  is  to  say,  so  that  under  the  in- 
fluence of  these  loads  the  elastic  stress  shall 
not  exceed  a  determined  ratio  of  the  loads 
capable  of  producing  rupture. 

Some  specialists  have  suggested  another 
mode  of  procedure  for  the  design  of 
structures  in  reinforced  concrete.  Instead 


t  Inge"nieurs  des  Fonts  et  Chaussees. 


[31] 


REINFORCED  CONCRETE 


of  deducing  the  elastic  stresses  from  the 
actual  loads,  their  method  involves  inquiry 
into  the  proportion  by  which  these  loads 
would  have  to  be  fictitiously  increased  to 
cause  rupture,  this  ratio  of  amplification 
determining  the  factor  of  safety. 

This  method  of  proceeding,  while  some- 
times interesting,  evidently  does  not  afford 
a  sufficient  guarantee  of  safety,  for  the 
sinking  of  a  building  is  never  caused  by  a 
proportional  amplification  of  the  loads  it 
has  to  support.  The  collapse  of  a  structure 
is  rather  the  consequence  either  of  an  acci- 
dental occurrence  or  of  an  internal  injury 
whose  development  becomes  destructive. 

Under  such  conditions  it  appears  proper 
to  design  structures  in  reinforced  concrete, 
as  in  the  case  of  other  constructions,  for 
the  most  unfavourable  loads  they  may 
have  to  support  and  with  such  a  factor  of 
safety  as  to  give  an  adequate  assurance  of 
stability. 

Although  the  first  method  is  obligatory, 
the  engineers  may  supplement  it,  if  they 
think  proper,  calculations  based  on  the 
amplification  of  real  loads  in  order  to 
ascertain  the  hypothetical  loads  capable  of 
causing  rupture,  and  they  may  state  the 
conclusions  they  deduce  from  these  calcula- 
tions. 

B.  —  Safe  Working  Stresses. 

4.  The  value  of  the  safe  working  stress 
in  compression  of  the  concrete  without 
reinforcement,  limited  to  2/7  of  its  crushing 
strength  after  90  days  hardening,  is  far 
higher  than  the  value  generally  allowed 
abroad.  The  figures  found  in  foreign  rules 
correspond  rather  to  an  allowance  */4  of  the 
crushing  strength  of  plain  concrete  of 
equivalent  proportions  after  28  days  setting. 

Making  comparison  between  the  two 
rules  for  three  mixtures  of  reinforced  con- 
crete examined  by  the  Commission  du 
Ciment  Arme,  the  following  results  are 
found: — 

The  mixtures  tested  by  the  Commission 
were  composed  of  400  litres  sand  and  800 
litres  gravel  and  respectively:  300  kilo- 
grammes; 350  kilogrammes;  400  kilo- 
grammes Portland  cement. 

The  ultimate  compressive  strength  found 
for  these  concretes  expressed  in  kilo- 
grammes per  square  centimetre  were  as  fol- 
lows : — 

[32] 


After  28  days. 

107    kilogrammes,    120    kilogrammes. 
133  kilogrammes — (a) 

After  90  days. 
160    kilogrammes,    180    kilogrammes, 

200  kilogrammes — (fr) 

Assuming  the  limit  of  the  safe  stress  be  a/4 
of  the  ultimate  strength  (a),  we  have  re- 
spectively : 

27  kilogrammes,  30  kilogrammes  and 

33  kilogrammes  per  cm2. 
Admitting    on     the     contrary    2/7    of     the 
strength    (fe)    according    to    Article    4    of 
Instructions,  we  have : 

45.7  kilogrammes,  51.4  kilogrammes, 

and  5.71  kilogrammes  per  cm2, 
or  almost  double  the  previous  values, 

Therefore,  from  this  standpoint,  Article 
4  appears  far  bolder  than  the  foreign  rules. 
But  these  latter  being  relatively  old,  may 
soon  be  revised  and  probably  modified  so 
as  to  come  into  line  with  the  provisions  of 
Article  4. 

As  French  designers  comply  more  wil- 
lingly that  foreign  engineers  with  adminis- 
trative regulations  even  for  private  works, 
the  boldness  of  Article  4  will  be  favourable 
to  the  development  of  the  reinforced  con- 
crete industry.  In  any  event,  designers 
remain  liable  for  the  data  they  apply. 

Otherwise  the  engineers  are  not  obliged 
to  adopt  the  ultimate  limit  of  the  allow- 
ance; they  can  prescribe  lower  limits  and 
should  remember  that  whatever  stress 
limits  may  be  adopted,  the  stability  of 
structures  in  reinforced  concrete  depends 
very  largely  upon  the  perfect  quality  of  the 
ingredients,  their  mathematical  admixture, 
and  their  accurate  application.  Supervision 
is  to  be  still  more  rigorous  for  such  struc- 
tures than  for  those  in  ordinary  materials. 

5.  The  intelligent  use  of  the  metal,  not 
only  for  longitudinal  but  also  for  the  trans- 
verse and  oblique  reinforcements,  is  to  be 
encouraged,  in  order  that  it  may  be  able  to 
assist  the  concrete  to  withstand  the  buckling 
action  due  to  longitudinal  pressures.  Un- 
der these  conditions  crushing  strength 
increases  very  largely,  and  when  the  trans- 
verse reinforcement  constitutes  hooping  of 
sufficiently  close  spacing  this  increase  is 
considerable,  as  experiments  have  shown. 
Therefore,  a  higher  allowance  for  the  safe 
working  stress  seems  logical,  and  this 
increase  is  to  be  determined  by  the  volume 


FREXCH  RULES  OX  REINFORCED  CONCRETE 


and  the  suitable  arrangement  of  the  trans- 
verse reinforcement.  It  would  be  difficult 
to  ascertain  the  laws  governing  this 
increased  resistance.  Some  tests  made  in 
laboratories,  or  carried  out  in  works,  in 
prisms  of  concrete  without  reinforcements 
and  with  suitable  transverse  reinforcement, 
suggest  the  rate  of  increase  of  the  crushing 
strength  of  the  latter,  and,  therefore,  the 
corresponding  amplification  of  the  safe 
working  stress  to  be  allowed.  Neverthe- 
less, according  to  the  experiments  made  by 
the  Commission  du  Ciment  Arme,  it  must 
be  admitted,  faute  de  mieux,  that  the  trans- 
verse reinforcement  and  the  hooping  mul- 
tiply the  crushing  strength  of  a  prism  of 
concrete  by  a  coefficient : 

,  V' 
i+m  v 

V  being  the  volume  of  the  tranverse  or 
oblique  reinforcement  and  V  the  volume 
of  concrete  corresponding  to  the  same 
length  of  prism;  m'  is  a  coefficient  vary- 
ing with  the  degree  of  efficiency  of  the 
bond  provided  between  the  longitudinal 
bars.  This  bond  being  realised  by  trans- 
verse ties  constituting  rectangles,  if  pro- 
jected on  a  cross  section  of  the  prism,  the 
coefficient  m'  may  vary  from  8  to  15,  the 
mini  inn  m  relating  to  a  spacing  of  the  trans- 
verse reinforcements  equal  to  the  least 
dimension  of  the  specimen  considered,  and 
the  maximum  corresponding  to  a  spacing 
equal  at  least  to  the  third  part  of  that 
dimension. 

When  the  transverse  reinforcement  is 
compounded  of  more  or  less  close  windings, 
in'  may  vary  from  15  to  32,  the  minimum 
being  applied  to  windings  spaced  2/3  of  the 
least  transverse  dimension  of  the  specimen 
considered,  and  the  maximum,  if  this  spac- 
ing reaches  YS  of  the  above  dimension  for  a 
longitudinal  pressure  of  50  kilogrammes 
per  square  centimetre,  or  a/s  of  the  above 
dimension  for  a  longitudinal  pressure  of 
ico  kilogrammes  per  square  centimetre. 

But  in  any  case,  whatever  may  be  the 
percentage  of  such  reinforcement  and  the 

,V 
value  of  the  coefficient  i+m',,-,  the  former 

indications  have  to  comply  with  the 
essential  condition  specified  in  Article  5, 
viz :  that  the  safe  working  stress  to  be 
allowed  must  not  exceed  8/3  of  the  strength 


of  plain  concrete,  such  as  are  described  in 
Article  4.  The  effect  of  this  requirement 
is,  in  every  case,  to  keep  the  working  stress 
within  such  limits  as  not  to  exceed  one- 
half  of  the  pressure  causing  the  first  sur- 
face cracks  in  the  reinforced  concrete; 
which,  according  to  the  experiments  of  the 
Commission  du  Ciment  Arme,  may  exceed 
by  from  25  to  60  per  cent,  the  pressure 
causing  the  crushing  of  plain  concrete. 

II.  —  Calculations. 

9.  This  article  requires  no  explanation  or 
comment. 

10.  The  scope  of  this  article  is  to  obviate 
empirical    methods     of     calculations.     The 
principles  of  the  elastic  theory  allow  safer 
solutions  in  the  case  of  reinforced  concrete 
as  for  ordinary  structures.     It  may  be  ad- 
mitted   within    the    limits    of    experimental 
researches  known  up  to  date,  that  Navier's 
theory    of    the    plane    deformation    of    the 
cross  section  can  be  applied  here  also. 

This  latter,  coupled  with  the  principle  of 
proportionality  between  deformation  and 
stress,  is  sufficient  in  the  case  of  members 
subjected  to  pressure,  if  every  heteroge- 
neous section  is  replaced  by  a  hypothetical 
section  having  the  same  mass  as  the  real 
heterogeneous  section,  and  if  a  density  i  is 
imputed  to  the  concrete  features  and  a  cer- 
tain density  in*  to  the  longitudinal  rein- 
forcements. Theoretically,  the  density  m 
would  be  the  ratio  : — 

Es 

—  EC"    <'>• 

of  the  modulus  of  elasticity  Es  of  the  rein- 
forcement to  the  modulus  of  elasticity  of 
concrete  EC.  The  value  of  this  ratio  is 
about  10  within  the  limits  of  loads  assumed 
in  Article  4.  It  increases  with  the  loads  of 
concrete,  and  may  double  or  triple  when 
rupture  occurs  by  crushing ;  it  will  decrease, 
on  the  contrary,  in  case  of  rupture  caused 
by  failure  of  the  reinforcement. 

This  fact  would  suffice  to  show  the  incer- 
titude of  calculations  based  on  a  fictitious 
increase  of  loads  up  to  rupture,  as  stated  in 
Article  3. 

In  all  cases  the  experiments  in  view  of 

*  The  transverse  reinforcement  has  nothing  to  do 
here.  Its  essential  effect  is  already  taken  in  con- 
sideration in  permitting  increase  of  (Article  5)  the  safe 
limit  of  the  compression  of  concrete.  In  fact  the  lead- 
ing efficiency  of  the  transverse  reinforcement  is  to 
increase  the  crushing  strength  of  concrete  by  with- 
standing the  transverse  buckling. 

[33] 


UNIVERSITY  OF  CAUFORHIA 


REINFORCED  CONCRETE 


the  determination  of  EC  were  made  with 
plain  concrete.  To  what  extent  the  ratio  m 
deduced  from  those  experiments  may  be 
applied  to  reinforced  concrete?  That  de- 
pends, probably,  on  the  degree  of  facility 
with  which  the  members  may  be  rammed 
in  all  their  parts  for  a  complete  embedding 
of  the  reinforcement. 

Therefore,  it  is  preferable  to  consider  the 
coefficient  m  as  resulting  from  tests  and  not 
necessarily  as  representing,  in  a  member 
with  complex  longitudinal  and  tranverse 
reinforcement,  the  ratio  of  the  elastic  mod- 
uli of  the  metal  and  of  the  concrete  tested 
separately. 

It  will  be  assumed  that  this  coefficient 
may  vary  from  8  to  15.  The  minimum  is  to 
apply  to  diameters  of  longitudinal  bars 
equal  to  l/w  the  least  dimension  of  the  mem- 
ber, the  ties  or  tranverse  reinforcement 
being  spaced  apart,  this  latter  dimension, 
and  having  their  ends  sufficiently  near  the 
surface  of  the  concrete.  The  maximum  is 
to  be  applied  in  the  case  of  diameters  of 
bars  equal  to  V2o  of  the  least  dimension  of 
the  member,  and  their  spacing  reduced  to 
1/s  of  this  dimension. 

Most  authors  admit  a  constant  value  for 
m  and  often  take  w=i5.  By  so  doing,  they 
may  ascribe  in  many  cases  too  much 
strength  to  the  metal  and  too  little  to  the 
concrete  in  relation  to  the  stresses  really 
occurring.  In  consequence  of  this  assump- 
tion, the  working  stress  of  concrete  may  be, 
in  fact,  higher,  and  the  factor  of  safety 
lower  than  is  presumed. 

Letting  m  vary  from  15  as  maximum  to  8 
as  minimum  according  to  the  disposition  of 
the  reinforcement,  longitudinal  and  tran- 
verse as  well,  the  truth  is  approached  more 
nearly,  and  compensation  is  found  for  the 
rather  high  working  stress  allowed  in  Arti- 
cle 4. 

Once  the  coefficient  m  has  been  decided, 
it  is  easy  to  apply  formulae  under  the  class- 
ical form  dealing  with  homogeneous  bodies. 

(a)  Simple  compression. — The  hypotheti- 
cal homogeneous  sectional  area  ft  is  given 
by  the  relation: — 

ft  =  ft+-;Wft    (2), 

ftc,  being  the  sectional  area  of  concrete 
and  fts  the  total  area  of  the  cross  sections 
of  the  longitudinal  reinforcement.  The 
latter  being  very  little  in  proportion  to  the 

[34] 


first,  it  should  be  noted  that  we  may  con- 
sider the  total  area  ftc  +  fts  instead  of  ftc  of 
the  member. 

Let  N  be  the  total  pressure  acting  nor- 
mally to  the  section,  Re  the  pressure  per 
unit  area  borne  by  the  concrete,  and  Rs  the 
compression  supported  by  the  reinforce- 
ment, we  get : — 

_N  N 

"ft'  -wft      ••••     (3). 

Re  being  assigned,  ft  is  deduced  and  then, 
by  means  of  formula  (2),  according  to  the 
actual  shape  of  the  member,  the  total  area 
fts  of  the  reinforcement  or  the  percentage: — 

a 

ftc' 

(fe)  Compression  with  flexure. — If  the 
total  compression  N  is  not  uniformly  dis- 
tributed, besides  the  area  ft  of  the  hypothet- 
ical section,  resort  must  be  had  to  the  centre 
of  gravity  of  the  section  and  to  its  moment 
of  inertia  about  the  perpendicular  to  the  di- 
rection of  flexure  drawn  through  the  center 
of  gravity,  according  to  the  following  equa- 
tions : — 

fly  =.  ftjj/,.  -+-  wiQyR     (4), 

I  —  L+mL  (5). 

Fig.  i  is  a  diagram  of  the  section  con- 
sidered, assumed  to  be  symmetrical  about 
the  axis  y'y.  The  centre  of  gravity  of  the 
hypothetical  section  ft  to  be  ascertained  is 


G  ;  that  of  the  reinforcement  Gs  is  known  ; 
that  of  concrete  Gc  is  also  known.  These 
points  are  determined  by  their  respective 
ordinates  :  — 


starting  from  the  axis  x'x,  arbitrarily  chosen, 
and  expressed  conventionally  with  the  +  sign 
when  on  one  side,  and  with  —  sign  when 
on  the  opposite  side.  Equation  (2)  gives  ft; 


FRENCH  RULES  ON  REINFORCED  CONCRETE 


then  equation  (4)  gives  the  ordinate  of  the 
centre  of  gravity  G  of  fi  ;  next,  the  axis 
xGx'  being  known,  the  moments  of  inertia 
Ic  and  Is  of  the  geometrical  areas  of  con- 
crete, and  logitudinal  reinforcement  can  be 
computed  about  that  axis,  and  finally,  equa- 
tion (5)  gives  the  moment  of  inertia  I  of  the 
hypothetical  section  fi,  about  the  same  axis. 

It  was  said  above  that  the  total  section 
fit  =  fle  +  fi,  of  the  member  is  sometimes 
taken  instead  of  the  section  fie  of  concrete. 
If  not  so  taken,  equations  (2),  (4)  and  (5) 
may  be  written  more  handily  in  practice  by 
inserting  the  total  area  instead  of  fie,  the 
area  of  concrete. 

Then,  inserting  instead  of  the  centre  of 
gravity  Gc  of  concrete  (that  Gt),  of  the  total 
section,  and  instead  of  the  moment  of  iner- 
tia, Ic  of  the  sectional  area  of  concrete  about 
the  axis  x'x  the  moment  of  inertia  It  of  the 
total  Section  about  an  axis  parallel  to  x'x 
passing  through  the  centre  of  gravity  Ct. 

The  formulae  then  become:  — 

fi  =  fi  +  (m  —  i)  fiy> 

fly  =  flyt  +  (m  —  I)  fly,, 


Then,  N  being  the  total  pressure  and  M  the 
bending  moment,  or  the  sum  of  the  mo- 
ments of  external  forces  acting  on  the 
section  considered  about  the  centre  of 
gravity  G  of  the  hypothetical  section,  the 
unit  pressure  nc  acting  on  the  concrete  at 
any  distance  v  from  the  axis  x'x  will  be:  — 


and  if  at  the  point  considered  there  is  a  bar 
of  reinforcement,  its  corresponding  stress 
would  be : — 


In  these  formulae,  the  distance  v  is  to  be 
considered  as  positive  on  the  side  where 
the  bending  moment  causes  compression, 
and  as  negative  on  the  opposite  side.  If 
the  bending  moment  about  the  axis  x'x  is 
considered  positive  from  left  to  right  for 
an  observer  placed  on  x'x,  the  head  in  x', 
the  feet  in  x,  then  the  distances  v  are  to  be 
considered  positive  for  the  points  of  the 
section  located  at  the  right  of  x'x  and  nega- 
tively for  those  laying  at  left. 

Let  us  call  vc  the  distance  from  x'x  of  the 
extreme  fibres  at  the  right  hand,  Vic  the 
absolute  value  of  the  same  distance  for  the 


extreme  fibres  at  the  left  hand,  the  maxi- 
mum compression  of  concrete  Rc  per  unit 
of  area  will  be: — 


The  minimum  compression  Rie  will  be: — 

R,  =  *--%.  .(7). 


Replacing  the  suffix  c  by  ^  for  the  rein- 
forcements, the  maximum  values  of  com- 
pression for  the  reinforcements  will  be:  — 


(8'). 


These  formulas  assume  essentially  that 
there  is  compression  at  all  points,  or,  in 
other  words,  that  the  value  Ric  and  there- 
fore the  value  Ris  are  positive.  If  RJs  were 
negative  they  could  not  be  applied,  because 
the  laws  of  extension  of  concrete  differ 
essentially  from  those  governing  its  com- 
pression. The  proper  process  will  be  indi- 
cated hereafter. 

If  we  know  the  total  pressure  N  in 
amount  and  direction,  that  is,  if  we  know 
the  position  of  its  point  of  application  (cen- 
tre of  pressure)  determined  by  its  co-ordin- 
ate v0  about  the  axis  x'x,  it  can  |pe  deduced 
by  definition  that  — 

M  =  Nv0  .  (9) 


Thenwriting: 

I  =  fir2 


(10) 


r  being  the  radius  of  gyration  of  the  hypo- 
thetical section  about  the  axis  x'x,  we 
should  get:  — 

N 


The    neutral    axis    would    be    obtained    by 
expressing  the  value  n0  =  o,  or:  — 


—  O 


(12) 


if  we  call  v   the  value  of  v,  determining  the 
position  of  tnife-'axis. 

With  these 'new   notations,   equation  (7) 
becomes: 

XT      /  _.    -.         \ 

(13) 


Comparison    of    the    two    last    formulae 
shows,  as  it  ought,  that  there  is  compres- 

[35] 


REINFORCED  CONCRETE 


sion  at  all  points  only  when  the  neutral  axis 
falls  outside  the  section,  or: 

—  V    >  Vic. 

The  above  consideration  supposes  that  the 
values  of  N  and  M  are  known  for  every 
section.  Such  will  be  the  case  for  a  column 
bearing  a  central  load  that  is  applied  in  the 
centre  of  gravity  of  the  hypothetical  section, 
where  M=o,  or  eccentric,  where  (M  =  Nv0). 
It  will  similarly  be  the  case  in  a  dam  for 
which  the  line  of  pressures  gives  in  fact  N 
and  v0  for  every  section. 

When  these  values  are  not  given  directly 
by  static  methods,  as  in  the  arch  of  a  bridge, 
it  is  necessary  to  proceed  as  in  the  far  most 
general  case  of  members  at  once  compressed 
and  extended,  a  case  which  really  justifies 
the  use  of  reinforcement,  and  we  enter  nat- 
urally upon  the  treatment  of  the  case  dealt 
with  by  Articles  n  and  12  of  the  Instruc- 
tions. 

It  was  stated  in  that  Article,  that  in  cal- 
culations dealing  with  deformation,  the  ten- 
sile strength  of  concrete  is  to  be  taken  into 
account.  These  calculations  are  necessary 
when  the  deformation  is  to  be  determined, 
particularly  to  estimate  the  deflection  taken 
by  the  work.  But  in  every  case  these  for- 
mulae of  deformation  are  to  be  applied  for 
computing  in  all  sections  the  pressure  N  of 
the  average  fibre  (geometrical  locus  of  the 
centres  of  gravity  G  of  the  hypothetical 
sections  0),  the  bending  moment  M,  and 
the  shearing  stress  T,  when  they  cannot  be 
determined  by  static  methods. 

By  definition,  N  and  T  are  the  normal 
and  tangential  components  of  the  external 
forces,  including  the  reaction  of  the  support 
acting  on  a  determined  side  of  the  section, 
and  M  is  the  sum  of  the  moments  of  the 
same  external  forces  about  the  point  G. 

In  the  case  of  a  column  with  one  end  free, 
or  of  a  beam  simply  supported  at  the  ends, 
the  forces  N  and  T  and  the  couple  M  can  be 
accurately  computed.  Hence  no  formula  of 
deformation,  and  therefore  no  assumption, 
are  required  in  order  to  determine  them. 
Article  n  does  not  deal  with  this  part  of 
the  subject. 

But  in  the  case  of  built  in  or  continuous 
beams,  extending  over  several  supports,  or 
of  arches  subject  to  tensile  stresses,  the 
.general  rule  for  arches  of  reinforced  con- 

'[36] 


crete    (Article    n)    is    to   be   applied,    and 
consequently  wants  to  be  interpreted. 

The  engineers  may  accept  the  usual  inter- 
pretation although  inaccurate,  while  assum- 
ing for  concrete  subjected  to  tension  the 
same  coefficient  of  elasticity  as  when  sub- 
mitted to  compression. 

This  assumption  once  made,  the  foregoing 
formulae  may  be  applied  in  their  entirety, 
under  the  essential  restriction  that  compres- 
sive  stresses  only  are  dealt  with. 

Now  it  is  easy  to  see  that  these  formulae, 
owing  to  the  intervention  of  the  features  of 
the  hypothetical  section  tt,  permit  us  to  sub- 
stitute for  the  problem  of  resistance  of  a 
reinforced  concrete  member— that  is  of  a 
heterogeneous  member — by  a  problem  of 
resistance  of  a  hypothetically  homogeneous 
member.  Then  all  the  general  and  classi- 
cal results  deduced  in  respect  of  the  latter 
case  may  be  applied  to  the  former,  and  in 
consequence,  in  order  to  compute  the  values 
of  N,  M  and  T  for  an  arch,  and  the  values 
of  M  and  T  in  the  case  of  a  beam  trans- 
versely loaded — where  N=o,  as  the  reac- 
tions over  the  supports — it  will  suffice  in 
every  case  to  insert  the  well-known  values 
referring  to  homogeneous  members. 

So,  if  we  have  a  reinforced  concrete  beam 
with  a  span  /,  built  in  at  both  ends  and  sup- 
porting a  uniformly  distributed  load  of  p 
kilogrammes  per  lineal  unit,  it  will  be  ad- 
mitted as  for  an  homogeneous  beam,  that 
the  maximum  bending  moment  developed 

at  the  ends  will  be  ,  and  that  the  bending 
moment  at  the  centre  will  be  of  opposite 
sign  and  equal  in  absolute  value  to  — . 

For  a  beam  with  the  ends  partially  built  in 

pp 
the  intermediate  value          may  be  adopted 

between        and  ~  for  a  beam  free  on  both 
24 

supports. 

In  the  same  way,  for  a  continuous  beam 
extending  over  several  supports  generally 
equidistant  the  values  given  by  treatises  on 
the  strength  of  materials  for  bending  mo- 
ments, shearing  forces  and  reactions  of  the 
supports,  for  homogeneous  members,  may  be 
applied,  or  in  special  cases,  may  be  deter- 
mined directly  in  the  same  manner  as  for 
homogeneous  members. 

In  llic  same  way,  for  the  design  of  arches 


FRENCH  RULES  ON  REINFORCED  CONCRETE 


the  tables  of  M.  Bresse  relative  to  homo- 
geneous arches  may  be  used  to  compute 
the  thrust  of  a  two-hinged  arch,  and  the 
tables  lately  published  by  M.  Pigeaud  in  the 
Annales  des  Fonts  et  Chaussees,  on  the  case 
of  an  arch  built  in,  and  intermediate  values 
may  be  adopted  between  those  given  by 
these  tables  if  the  building  in  is  thought  to 
be  only  partial. 

In  special  cases  the  thrust  will  be  directly 
computed  by  the  classical  formula  for 
homogeneous  members. 

The  thrust  and  the  vertical  reaction  once 
known,  all  the  necessary  data  will  be  at 
hand  to  determine  M,  N  and  T  graphically 
or  mathematically  for  any  desired  section. 

More  Accurate  Interpretation, — The  ten- 
sile strength  of  concrete  may  be  taken  in 
account  more  accurately  if  we  admit  as  re- 
sulting from  various  experiments  the  fol- 
lowing principle :  the  modulus  of  elasticity 
of  reinforced  concrete,  subjected  to  tension, 
may  be  considered  nearly  constant  until  the 
ultimate  tensile  strength  of  the  same  con- 
crete without  reinforcements  is  reached; 
the  material  becomes  to  some  extent  plastic, 
that  is,  it  is  lengthened  in  consequence  of 
its  connection  with  the  reinforcement,  but 
without  any  alteration  of  its  ultimate 
strength  in  tension.  There  is  no  difficulty 
in  setting  up  a  theory  of  the  resistance  of 
materials  based  on  this  hypothesis,  coupled 
with  the  assumption  of  Navier  concerning 
the  plane  deformation  of  cross-sections. 
But  the  calculations  become  far  more  com- 
plicated. However,  the  engineers  may  re- 
commend this  method  if  they  find  it  more 
suitable. 

Whatever  may  be  the  method  adopted 
for  the  determination  of  the  values  of  the 
bending  moment  M,  of  the  shearing  force 
T,  and  of  the  pressure  of  the  average  fibre 
(which  is  zero  in  the  straight  beams  tran- 
versely  loaded),  the  local  stress  is  to  be 
deduced,  at  any  rate  for  the  most  heavily 
loaded  sections.  Article  n  prescribes  that 
the  tensile  strength  of  concrete  is  not  to  be 
considered  for  that  object.  This  require- 
ment is  not  at  all  contradictory  with  the 
prescription  that  it  should  be  taken  into 
account  for  the  calculation  of  deformation. 
Tn  fact,  the  cracks  of  the  concrete  are  more 
or  less  of  importance  near  the  reinforce- 
ment in  tension,  but  the  alteration  of  the 
general  deformation  of  the  structure  caused 


by  these  hair  surface  cracks  is  scarcely  ap- 
preciable, even  if,  at  a  point,  a  more  appar- 
ent crack  is  produced.  But  at  any  such 
point  the  local  stress  would  obviously  be 
extensively  increased.  It  is,  therefore,  pro- 
per to  admit  this  favourable  hypothesis  in 
the  calculation  of  local  stresses,  while  it 
would  be  improper  to  admit  them  in  the  in- 
vestigating of  general  deformation,  and 
consequently  for  the  computation  of  the 
values  of  M,  T,  N  depending  upon  them. 

Application  to  a  Slab  in  Combination  with  a 
Rectangular  Beam. 

We  will  now  apply  the  method  stated 
above  to  a  slab  (Fig.  2) ,  assimilated  to  a  T 
beam,  the  height  of  which  is  h,  the  breadth 
of  the  flanges  is  b,  the  breadth  of  the  rib  is 
b',  the  depth  of  the  slab  is  e,  and  the  total 
sectional  area  of  the  reinforcement  in  com- 
pression is  w,  its  average  distance  from  the 
compression  face  is  d;  the  sectional  area  of 
the  reinforcement  in  tension  is  a/,  its  dis- 
tance to  the  tension  face  is  d '.  If  the  for- 
mer reinforcement  does  not  exist,  w=o. 

Let  y  be  the  unknown  distance  of  the 
neutral  axis  xx  from  the  compressed  face 
B.  In  Fig.  3  the  section  of  the  slab  is  pro- 
jected about  the  straight  line  AB.  The 
ordinates  of  the  straight  line  XB'  represent 
the  pressures  of  concrete,  and  if  m  is 
neglected  the  ordinate  bb'  represents  the 
pressure  of  the  compressive  reinforcement, 
and  aa'  represents  the  stress  of  the  tensile 
reinforcement.  Let  K  be  the  angular  co- 
efficient or  trigonometrical  tangent  of  the 
angle  B'xB. 


(a)  Simple  Flexure. — In  case  of  simple 
flexure  N=o.  Assuming  that  the  elastic 
forces  are  limited  to  the  couple  of  flexure 
M,  that  is,  their  sum  =O — and  the  sum  of 
their  moments  about  any  point — for  instance, 
about  the  point  B — is  equal  to  M;  then  the 
distance  XB=yi  of  the  neutral  axis  from 
the  compressed  face  is  given  by  the  quad- 
ratic equation:— 

[37] 


REINFORCED  CONCRETE 


0  = 


i  —      }+mu(yi—d) 


—m<a'(h—a'—yi)  ............     (16), 

then   to    determine    the    angular    coefficient 


-mu  (h-d  -*-yi)  (h—d)  ........  (17)  , 

where  the   second   term    and    M    also   are 
known. 

These  formulae  presuppose  that  the  neutral 
axis  is  included  in  the  rib;  if  included  in  the 
slab,  it  suffices  to  make  b'=b  in  the  previous 
formula,  and  we  get:  — 

fry* 

o=—  —  \-m*a(yi  —  d)  —  mw'(h—  d  —  yi)  .  .  (18), 

M    bvis 

' 


(h-d)  ................  (19). 

To  ascertain  where  the  neutral  axis  falls, 
and,  therefore,  to  know  which  of  the  two 
formulae,  (16)  or  (18),  is  to  be  employed, 
it  suffices  to  substitute  in  the  second  term 
of  (16)  e  for  yi.  Whence  we  have:— 

If  the  numerical  value  of  this  expression 
is  positive,  the  neutral  axis  falls  within  the 
slab  and  is  to  be  computed  by  means  of  for- 
mula (18).  If  this  value  is  negative,  the 
proceeding  is  inverted. 

Formula  (17)  and  (19)  may  be  applied  also 
to  a  rectangular  section,  the  base  of  which 
is  b  and  the  height  h. 

The  two  unknown  quantities  y,  and  K 
being  determined,  the  maximum  compres- 
sion Re  of  the  concrete  will  be:— 

Rc=Kyi  ........  (20) 

The  compressive  stress  Rs  and  the  tensile 
stress  R's  will  be:— 


(b}  Compression  in  Combination  with 
Flexure.—  In  this  case  we  know  the  pres- 
sure N  and  the  position  of  the  centre  of 
pressure  C,  the  point  of  application  of  the 
resultant  of  the  external  forces.  Let  us  call 
c  the  distance  of  this  point  from  the  com- 
pression face,  this  distance  being  positive  if 
C  falls  inside  the  section,  and  negative  in 
the  opposite  case.  It  appears  more  suitable 
in  this  case  (it  will  be  said  why  later)  to 
[38] 


determine  the  position  of  the  neutral  axis  by 
means  of  its  distance  XC=yi  (Fig.  3)  from 
the  centre  of  pressure  C  rather  man  by 
means  of  its  distance  yi  from  the  compres- 
sive face.  Therefore  the  sum  of  the  moments 
of  the  elastic  forces  about  C  is  zero,  and  we 
obtain  an  equation  for  the  determination  of 
ya  or  of  the  position  of  the  neutral  axis  xc'x. 
In  the  case  when  this  axis  falls  inside  the 
rib,  this  equation  is  the  following:  — 


a+£—  d)  (—  c+d) 
-m<a'(h-d-c-y*)(h-d'-c)..(22). 

We  see  that  this  equation  is  of  the  form:  — 
yj+pyz+g=o  ............  (23) 

the  numerical   coefficients  known  p  and  q 
have  the  following  expressions:— 


1  (24). 


The  term  y2  missing,  the  resolution  of 
the  equation  is  more  easy  and  justifies  the 
use  of  the  unknown  quantity  y2. 

When  y2  is  known,  the  unknown  auxil- 
iary quantity  K  is  immediately  given  by  the 
equation:  — 


(y-2  +  c—  d]  —  nua  (h—d  —c—yi  ) 
......  (25), 

where  the  second  term  and  N  are  known. 

These  formulae  assume  the  neutral  axis  to 
fall  inside  the  rib.  If  falling  inside  the  slab, 
or  in  the  case  of  a  rectangular  section  with 
base  b  and  height  h,  it  suffices  to  make 
b'  =  b,  and  we  get: 


(26). 


,      , 
-d)+-~-(h-d-c] 


Finally  in  the  case  of  a  slab,  to  ascertain 
whether  the  neutral  axis  falls  inside  the 
rib  or  the  slab,  we  have  only  to  make 


FRENCH  RULES  ON  REINFORCED  CONCRETE 


y2  =  —  c+e  in  the  first  term  of  equation  (23) 
and  in  its  derivative  taken  about  y2,  then:  — 


I 


, 

27)* 


If  the  numerical  values  of  these  two  ex- 
pressions are  of  opposite  sign,  the  neutral 
axis  falls  inside  the  rib  ;  if  they  are  of  the 
same  sign  the  neutral  axis  falls  inside  the 
slab. 

When  the  unknown  quantities  y2  and  K 
are  determined,  it  will  be  deduced  from  the 
first  that:  — 

y1=y2  +  C    ........    (2S) 

for  the  distance  of  the  neutral  axis  from 
the  compressed  face.  Then  the  unit  com- 
pressive  stress  Re  of  concrete,  the  unit 
compressive  stress  Rs,  and  the  unit  tensile 
stress  R's  of  the  reinforcements,  will  be 
determined  by  means  of  equations  (20) 
and  (21). 

Remarks  Dealing  with  the  Design  of  Slabs. 

When  a  floor  is  constituted  by  a  slab  in 
combination  with  ribs  (Fig.  4),  one  rib  is 
separated  from  the  whole  with  two  project- 
ing portions  of  the  slab  in  order  to  consider 
only  the  segment  aa'jSjS'  of  breadth  aft—  b, 
neglecting  the  assistance  that  this  portion 
of  floor  may  receive  owing  to  its  adhesion 
with  the  neighbouring  parts. 


This  breadth  b  is  to  be  computed  in  rela- 
tion to  the  depth  e  of  the  slab,  to  the  spac- 
ing L  of  the  ribs  and  to  their  span  L.  It  is 
desirable  never  to  exceed  for  the  breadth  b 
one-third  of  the  span  /;  nor  three-fourths 
of  the  spacing  of  the  ribs. 

As  regards  the  floor  itself,  if  it  has  to 
support  concentrated  loads  between  two 
ribs,  two  series  of  reinforcing  bars  are 
to  be  provided ;  giving,  as  a  general  rule, 
to  the  smaller  a  total  sectional  area  per 
unit  of  breadth  equal  to  half  of  that  of 
the  greater. 

Then,  in  the  calculation  of  the  floor  depth 
e,  the  concentrated  load  may  be  replaced  by 
a  load  uniformly  distributed  on  a  rectangle 


having  the  point  of  application  of  this  force 
as  centre,  its  sides  parallel  to  the  ribs  and 
its  breadth  e  equal  to  the  following  depths: 
(i)  that  of  the  slab  itself,  or  e;  (2)  that  of 
the  embankment  and  of  the  roadway ;  it 
bears  the  sides,  perpendicular  to  the  ribs, 
are  to  be  spaced  apart, 

e  H ,  L  being  the  spacing  of  the  ribs. 

«J 

The  load  being  distributed  in  such  a 
manner,  it  is  assumed  to  be  supported  by  a 

strip  of  slab,  the  breadth  of  which  is  e  + 

without  any  assistance  from  the  adjacent 
portions  and  consequently  by  a  beam,  of 

which  (e  H J  e  is  the  sectional  area  and  L 

the  span. 

In  the  case  of  a  slab  carried  by  two  right- 
angled     series    of     ribs;     with    respective 
spacings   L   and   L',    the   bending  moment 
parallel  to  the  span  L  may  be  calculated, 
faute  de  mieux,  by  considering  only  the  ribs 
of  which  the  span  is  L,  and  multiplying  the 
result  by  the  coefficient  of  reduction : — 
i 
L4' 

1  +  2- 

The  bending  moment  parallel  to  L'  will 
be  calculated  in  the  same  way,  substituting 
L  for  L'  and  vice  versa. 

Adhesion. — To  ensure  the  adhesion 
between  the  concrete  and  the  tensile  rein- 
forcement, for  instance,  it  will  be  observed 
that  if  in  two  neighbouring  sections  AB  and 
A'B'  of  a  member  (Fig.  5),  spaced  A  s  apart, 


fcoVP'j 


the  tensile  stress  of  the  reinforcement  has 
been  found  equal  to  R's  and  R"s  per  unit  of 
area,  the  total  tensile  stresses  over  these 
two  sections  will  be: — 

w'R's  and  w'R"s. 

[39] 


REINFORCED  CONCRETE 


Supposing,  for  instance,  R"s  >  R's,  the 
difference  w'(R"s—  R's\  will  tend  to  produce 
the  slipping  in  its  encasing  of  concrete  of 
the  portion  A  s  of  the  reinforcement.  There- 
fore, if  the  total  perimeter  of  the  tensile 
reinforcements  is  x',  the  adhesive  strength 
per  unit  of  area  will  be:  — 


The  value  of  this  ratio  is  not  to  exceed 
for  the  safe  adhesive  stress  prescribed  by 
Article  6. 

If  stirrups  or  other  transverse  reinforce- 
ments are  sufficiently  connected  with  longi- 
tudinal reinforcement  so  as  to  prevent  any 
slipping  of  these  latter  in  casing  of  concrete, 
then  the  shearing  stress  in  the  transverse 
reinforcements  along  A  s,  or  the  product  of 
the  total  sectional  area  which  is  in  shear  by 
the  safe  working  stress  allowed  for  the 
metal,  is  to  be  deducted  from  the  stress 
«'(R"s  —  R's),  and  it  suffices  that  the  ratio: 

co'R'.-R'Q-F 

*'AS 

does  not  exceed  the  safe  adhesive  working 
stress. 

But  mere  ties  connecting  the  transverse 
with  the  longitudinal  reinforcement  are  not 
sufficient  for  resisting  the  force  F.  These 
ties  are  necessary,  but  their  assistance  to 
the  adhesion  is  not  to  be  considered. 

Longitudinal  Slipping  of  Concrete  in 
itself  and  Shearing  Stress.  —  Let  us  con- 
ceive a  portion  of  the  member  limited  by 
the  two  cross-sections  AB  and  A'B'  (Fig. 
5),  spaced  A  s  apart,  and  including  the  long- 
itudinal tensile  reinforcement  a'b';  mn  is  a 
cross-section  made  in  the  tension  area  of 
the  concrete,  that  is,  between  the  reinforce- 
ment a'b'  and  the  plane  of  neutral  fibres. 
Let  w,;=:area  of  that  section. 

As  the  tensile  stresses  of  the  concrete 
normally  to  mB  and  nB'  are  not  taken  into 
account,  the  portion  mnBB'  is  balanced  by 
the  influence  of  tensile  stresses  w'  R"s  and 
w'  R's  of  the  reinforcement  and  of  the  longi- 
tudinal stress,  or  shearing  stress,  along  mn. 
Therefore,  this  stress  per  unit  of  area 


".-  R',) 


(a), 


must  not  exceed  the  safe  limit  allowed  for 
shear. 

If  transverse  reinforcement  efficiently  re- 

[40] 


sists  the  longitudinal  slipping,  it  is  allowed 
to  take  it  into  account,  as  stated  above, 
for  adhesion. 

This  stress  (a)  remaining  constant  as  far 
as  the  neutral  axis,  and  decreasing  further 
owing  to  the  effect  of  pressure,  the  amount 
above  considered  is  a  maximum. 

The  amount  of  the  shearing  force  at  any 
point  is  otherwise  equal  to  the  longitudinal 
slipping  above  referred  to. 

12.     Comparison  with  Flexure. 

Euler's  formula,  applied  with  a  suitable 
coefficient,  permits  the  design  of  a  compres- 
sion member  without  flexure. 

It  permits  computations  of  the'safe  load 
N  not  to  be  exceeded,  that  may  be  borne 
by  a  member  of  the  length  =  I,  hypotheti- 
cal section  =  fi,  minimum  radius  of  gyra- 
tion =  r,  relative  to  the  various  axes  passing 
through  the  centre  of  gravity  (for  symmet- 
rical members  the  radii  of  gyration  about 
the  bending  axis  or  normal  to  the  plane  of 
symmetry  are  generally  to  be  considered). 
The  expression  of  N  is:— 


<  U 

EC  is  the  modulus  of  elasticity  of  concrete 
(its  average  value  being  one-tenth  of  the 
modulus  of  elasticity  of  steel),  t  is  a  factor 
of  safety  and  K  a  coefficient  depending  on 
the  manner  in  which  the  ends  of  the  mem- 
ber are  fixed,  and  having  the  following 
values  :  — 


Methods  of  fix- 
ing the  ends. 


One  end  fixed  and 

the  other  free  . . 

Both  ends  rounded 

One  end  fixed  and 

the  other  rounded 


Both  ends  fixed  .   \ 


K 


Observations. 


If  the  fixing  is  im- 
perfect, an  aver- 
age value  is  to  be 
taken  between 
YL  and  i. 

If  one  of  the  fix- 
ings is  imper- 
fect, an  average 
value  is  to  be 
taken  between^ 
and  Y*  ;  if  both 
are  imperfect, 
between  kand  i. 


As  regards  the  factor  of  safety,  the  re- 
sults obtained  will  be  comparable  with  those 


FREXCH  RULES  OX  REINFORCED  CONCRETE 


given    by    Rankine's     formula     for    great 
lengths  in  admitting:  — 

y   =   IOOOR., 

Re    being    the    safe    compressive    working 
stress  allowed  by  Articles  (4)  and  (5)  of 
the  Instructions.     We  then  shall  have  :  — 
i  ooo  Re  w-fir2 

-ir 

or  approximately:  — 

loooR,  OH 
~  ' 


III.—  Part  iy. 

The  Instructions  concerning  the  practical 
construction  of  works  and  tests  repuire 
neither  comment  nor  explanation. 


It  will  be  remembered  that  the  reliability 
of  works  in  reinforced  concrete  is  largely 
based  upon  their  perfect  construction.  The 
accidents  which  have  occurred  in  the  past 
have  been  due,  as  a  rule,  to  bad  selection 
or  preparation  of  materials.  Specially 
stringent  supervising  is,  therefore,  to  be  ex- 
ercised on  the  nature  and  clearness  of  the 
materials,  on  their  mixture,  the  amount  of 
water  employed,  the  ramming  and  forcing 
the  concrete  along  and  around  the  rein- 
forcement, and  the  correct  disposition  of 
these  latter,  etc. 

As  for  tests,  they  may  be  simplified  in 
some  cases  if  justified;  but  it  would  not 
be  proper  to  endeavor  to  save  money  or 
trouble  if  these  advantages  involve  the 
least  risk  to  the  public. 


[41] 


REINFORCED   CONCRETE 
CONSTRUCTION 

Its  advantages  as  a  structural  material  for  factories , 
together  with  a  description   of  re- 
inforcing systems 

By 
Walter   Mueller 

ABOUT  forty  years  ago  a  French  gardener,  Joseph  Monier  by 
name,  devised  and  patented  a  method  of  reinforcing  concrete, 
successfully  applying  it  in  the  construction  of  flower  pots.  From 
this  small  beginning  an  industry  has  been  developed  which  has 
revolutionized  building  construction,  and  in  the  opinion  of  authorities,  it 
marked  the  inception  of  the  greatest  advancement  made  in  building  con- 
struction since  the  introduction  of  structural  steel. 

Reinforced  concrete  is  a  technical  name  for  a  method  of  fireproof  con- 
struction in  which  the  only  materials  used  are  cement,  sand,  broken  stone 
and  steel.  Concrete  is  a  combination  in  proper  proportions  of  the  first  three, 
forming  a  hard  and  permanent  substance  similar  in  texture  and  hardness  to 
granite.  Any  good  building  material  must  resist  the  pressure  and  pull  of 
weights  and  stresses.  The  concrete  resists  the  pressure  and  the  steel  the 
pull.  The  proper  combination  of  these  two  gives  any  structure  capacity  to 
carry  weights.  Steel  is  added  to  the  concrete  to  produce  elasticity,  which  is 
essential  to  any  good  building  material.  This  addition  of  steel  is  called  rein- 
forcement— hence  the  name  reinforced  concrete. 

Although  the  application  of  reinforced  concrete  was  at  first  and  is  still 
mainly  confined  to  beams  and  floor  slabs,  entire  buildings  are  now  erected  of 
it,  comprising  factories,  office  buildings,  hotels,  apartment  houses,  churches, 
public  buildings,  grain  and  cement  bins,  smoke  stacks,  etc.  In  engineering 
construction  it  has  been  used  for  bridges,  sewers,  walls,  dams,  tanks,  etc.  In 
fact,  its  field  appears  to  be  almost  unlimited. 

To  the  manufacturer  reinforced  concrete  construction  is  of  peculiar  in- 
terest, due  to  the  advantages  concomitant  with  its  use  in  the  erection  of  fac- 
tories, warehouses,  etc. 

The  predominating  advantages  claimed  for  reinforced  concrete  con- 
struction are : 

(i.)  Economy.  (2.)  Ease  and  rapidity  of  erection.  (3.) Durability. 
(4.)  Fire-resisting  qualities.  (5.)  Impermeability  to  moisture.  (6.)  Even- 
ness of  temperature  and  deadening  of  sound.  (7.)  Monolithic  nature  of 
reinforced  concrete  structures. 

[42] 


REIXFORCED  CONCRETE  CONSTRUCTION 


THE    LARGEST    REINFORCED    CONCRETE    WAREHOUSE    IN    THE    UNITED    STATES.     BUILT    FOR 

FARWELL,    OZMUN,    KIRK    &    COMPANY,  ST.    PAUL,  MINN.,  AND    REINFORCED 

THROUGHOUT    WITH     THE     KAHN    TRUSSED    BAR 


REINFORCED    CONCRETE    WAREHOUSE    FOR    THE  OLIVER    CHILLED   PLOW   WORKS,  SOUTH  BEND, 
INDIANA.     KAHN   TRUSSED   BAR   USED   AS   REINFORCEMENT 

[43] 


REINFORCED  CONCRETE 

Economy 

The  main  item  making  for  economy  in  reinforced  concrete  construction 
is  the  unskilled  labor  which  is  employed  in  connection  with  it  to  so  large  an 
extent.  How  large  a  factor  this  is  and  how  its  importance  is  being  realized 
has  lately  been  shown  in  two  leading  instances. 

The  Greater  New  York  Executive  Counsel  of  the  Bricklayers'  Union 
has  recently  adopted  regulations  to  the  effect  that  whenever  and  wherever 
concrete  is  used  in  building  construction  within  the  limits  of  Greater  New 
York  the  work  must  be  done  by  union  bricklayers,  none  of  whom  will  here- 
after seek  or  accept  employment  from  any  contractor,  owner  or  architect 
failing  to  comply  with  this  requirement.  Moreover,  the  bricklayers  will 
insist  not  only  on  laying  concrete  blocks  and  making  concrete  floor  arches 
but  also  on  the  right  to  dump  the  concrete  into  forms,  which  has  heretofore 
been  done  by  laborers,  at  the  regular  bricklayers'  wages  of  seventy  cents  an 
hour.  The  work  of  laying  concrete  blocks  is  regarded  as  bricklayers'  work 
now. 

In  regard  to  the  laying  of  concrete  blocks  no  objection  can  be  made  by 
any  fair  minded  man  regarding  the  justice  of  this  particular  demand.  But 
when  it  comes  to  paying  bricklayers'  wages  for  dumping  concrete  into  forms 
a  horse  of  another  color  enters  the  arena  and  there  is  bound  to  be  a  clash 
between  the  union  and  the  builders.  The  outcome  of  this  struggle  will  be 
awaited  with  much  interest. 

In  the  reconstruction  of  San  Francisco  it  is  planned  to  use  reinforced 
concrete  to  a  large  extent  but  the  action  of  the  labor  unions  in  laying  all 
sorts  of  obstacles  in  its  way  will  undoubtedly  be  a  considerable  deterrent. 
Due  to  the  powerful  political  influence  wielded  by  the  labor  unions  in  San 
Francisco  they  are  directly  in  control  of  the  building  situation,  ?nd  reports 
indicate  that  reinforced  concrete  construction  the  only  form  of  construction 
adapted  to  successfully  withstand  seismic  disturbances  and  the,  in  most 
cases,  subsequent  conflagrations,  is  receiving  unmerited  opposition. 

Another  source  of  economy  in  reinforced  concrete  construction  lies  in 
the  comparative  lightness  of  structures  erected  according  to  this  method, 
thus  affecting  a  considerable  saving,  in  very  many  instances,  in  foundation 
work.  The  thinness  of  the  walls,  floors,  etc.,  more  than  compensates  for 
the  extra  cost  of  the  concrete  required  in  the  mixing  and  depositing  of  con- 
crete and  in  the  placing  of  the  reinforcement.  A  seven  or  eight-inch  rein- 
forced concrete  wall  will  replace  one  of  brick  twenty-five  inches  thick.  This 
would  amount  to  an  increase  in  available  renting  space  in  an  office  building1 
of  about  15%  and  a  proportionable  earning  in  the  investment. 

Objections  are  sometimes  raised  against  the  large  amount  of  false 
work  needed  for  forms.  As  this  false  work,  however,  is  usually  of  a  very 
simple  nature  it  requires  no  special  treatment  and  very  few  timbers  of  large 
size.  In  addition,  the  amount  of  false  work  is  largely  reduced  by  the  fact 
that  many  parts  of  the  building  can  be  molded  on  the  ground  before  erec- 
[44] 


REINFORCED  CONCRETE   CONSTRUCTION 


THE   CLINTON    REINFORCING   SYSTEM,  SHOWING  THE  METHODS  OF  USING  THE  FABRIC   ON   THii 
FLOORS  OF  THE  HARBOR  SHEDS  AT  MONTREAL 


3&&*tt?ttXtt*&^tt&& •;  &ZteK&*tttt*&&&JS^&tt*ti 


— ---i 


DIAGRAM   OF  SYSTEM   D,  TYPE  II,  OF  THE  CLINTON   REINFORCING  SYSTEM   PICTURED   AT  THE 
TOP   OF  THE   PAGE,  SHOWING   THE   METHOD   OF  EMBEDDING  THE   MESH 


[451 


REINFORCED  CONCRETE 

tion.  The  comparative  lightness  of  reinforced  concrete  arches  compared  to 
those  of  masonry  and  brick  work  permits  the  centering  to  be  much  lighter 
than  that  generally  employed. 

Rapidity  of  Erection 

The  ease  and  rapidity  with  which  a  reinforced  concrete  structure  can  be 
erected. constitute  two  of  the  greatest  advantages  of  this  form  of  construc- 
tion. Walls  can  be  molded  a  great  deal  quicker  than  they  can  be  built  of 
stones  or  bricks,  and  floors  and  roofs  are  molded  at  the  same  time  as  their 
supporting  beam's/-  -Another  point  making  for  rapidity  is  in  that  the  material 
employed  is  easily  procured  and  requires  no  such  treatment  as  that  of  dress- 
ing stone,  or  the  making  of  girders  to  dimensions. 

The  iron  or  steel  reinforcement  is  almost  entirely  in  the  form  of  round 
rods,  hoop  iron  or  wire.  The  reinforcement  is  in  most  cases  simply  laid  in 
place  or  perhaps. tied  with  wire  at  crossing  places  and  requires  only  such 
simple  blacksmith  work  as  can  be  done  at  a  portable  forge  at  the  site  of 
the  work,  or  the  pieces  may  be  cut  to  the  necessary  dimensions  before 
delivery. 

The  Durability  of  Reinforcements 

The  experience  of  thousands  of  years  has  demonstrated  that  concrete  is 
absolutely  indestructible.  That  it  resists  the  disintegrating  effects  of  air, 
moisture,  water  and  steam,  and  even  of  sea  water  and  of  sulphuric  and 
chlorine  gases.  Some  of  the  most  ancient  structures  in  the  world  are  built 
of  this  material  and  are  to-day  apparently  in  as  sound  a  condition  as  they 
were  at  the  time  they  were  first  completed.  In  fact,  they  are  sounder  be- 
cause tests  have  demonstrated  that  the  resistance  of  concrete  increases  with 
time. 

The  cost  of  maintaining  a  reinforced  concrete  structure  is  almost  noth- 
ing, comparing  more  favorably  in  this  respect  than  do  structures  erected  of 
steel  and  iron,  which  require  almost  as  continual  supervision  as  do  those 
erected  of  brick  or  stone. 

As  no  boring  animals  can  work  their  way  into  reinforced  concrete  struc- 
tures of  this  material,  therefore,  are  free  from  all  sorts  of  vermin.  Neither 
will  such  structures  harbor  microbes,  due  to  the  freedom  of  the  material 
from  pores.  Thus  in  the  matter  of  hygiene  reinforced  concrete  is  the 
most  satisfactory  material  for  the  construction  of  abattoirs,  factories,  ware- 
houses etc. 

The  Fireproof  Qualities  of  Concrete 

The  fire  resisting  qualities  of  reinforced  concrete  are  perhaps  of  great- 
est interest  to  the  manufacturer.  There  is  no  doubt  but  that  reinforced 
concrete  is  the  best  material  for  fireproofing  construction  since  concrete 
protects  the  embedded  skeleton  by  reason  of  its  low  conductivity  of  heat. 
This  was  shown  to  be  the  case  in  the  conflagrations  of  Baltimore  and  San 
[46] 


REIXFORCED  CONCRETE  CONSTRUCTION 


THE    FALSE    WORK,   SHOWING    THE    PRELIMINARY    STEPS    IN    THE    CONSTRUCTION     OF    A    CON- 
CRETE    FLOOR    REINFORCED    BY    THE    UNIT    SYSTEM 


PLACING    THE    UNIT    BARS    IN    POSITION    BEFORE    THE    OPEN    SPACES    ARE    FILLED    IN    WITH 

CONCRETE 


[47] 


REINFORCED  CONCRETE 

Francisco.  As  the  coefficients  of  expansion  of  concrete  and  steel  are  equal 
there  is  no  danger  from  collapse  in  a  reinforced  concrete  structure.  In  the 
case  of  terra  cotta  and  steel,  a  form  of  construction  which  is  being  rapidly 
supplanted  by  reinforced  concrete,  the  coefficient  of  the  former  is  double 
that  of  the  latter  and  therefore  collapses  are  bound  to  occur  under  high 
temperatures,  due  to  the  largely  increased  expansion  of  terra  cotta  over 
steel. 

Impermeability 

The  resistance  of  reinforced  concrete  to  the  penetration  of  water  is 
another  one  of  its  most  advantageous  properties  and  gives  it  a  distinct  ad- 
vantage over  brick  and  masonry  for  aqueducts,  reservoirs,  tanks,  etc.  For 
certain  industries  where  vats  and  big  tubs  are  used  reinforced  concrete  has 
proven  itself  far  superior  to  timber  and  it  has  been  found  to  withstand  the 
action  of  alkalis  and  acids  far  better  than  iron  or  wood. 

Equability  of  Temperature  and  Soundproof  Qualities 

The  poor  conducting  qualities  of  concrete  keep  the  rooms  erected  of  it 
at  a  very  equable  temperature.  This  is  a  special  advantage  where  they  are 
near  the  roof  as  in  ordinary  buildings,  where  they  are  apt  to  be  unbearably 
hot  in  summer  and  excessively  cold  in  winter. 

The  efrect  on  sound  is  the  reverse  by  consequence  of  the  wall  being 
thin.  And  where  single  walls  are  employed  sounds  penetrate  in  a  marked 
degree.  It  is  a  very  simple  matter  to  employ  double  walls  in  this  form 
of  construction  as  they  may  be  made  very  thin  and  united  by  bonding  in 
cross  ties,  so  that  the  two  walls  act  as  one  in  resisting  stresses.  Floors 
are  also  made  double,  the  ceiling  slab  being  separated  from  the  floor  slab. 
The  same  method  is  also  employed  in  the  construction  of  roofs. 

•  .      Monolithic  Nature  and  RigMity 

A  structure  of  reinforced  concrete  is  not,  as  is  sometimes  supposed,  an 
assemblage  of  parts  connected  together  in  a  more  or  less  thorough  manner. 
It  is  a  unit,  each  part  of  which  is  connected  with  the  neighboring  pieces. 
This  intimate  connection  gives  a  strength  to  a  structure  unknown  prior  to 
the  introduction  of  reinforced  concrete  and  also  affords  an  almost  perfect 
resistance  to  vibrations. 

This  resistance  is  perhaps  most  noticeable  in  buildings  containing 
machinery  where  the  absence  of  vibration  is  not  only  beneficial  to  the 
building  itself  but  also  to  the  machinery  in  it.  The  latter  runs  more 
smoothly  and  not  being  subject  to  external  vibration  enjoys  a  longer  life. 
Fast  "running  machinery  such  as  that  used'in  the  operation  of  dynamos  or 
centrifugal  pumps  is  especially  benefited  by  being  placed  in  buildings  of 
reinforced  concrete.  For  structures  on  bad  or  swampy  ground  reinforc- 
ed concrete  enjoys  a  peculiar  advantage.  A  reinforced  platform  under  the 
building  supported,  if  necessary,  on  reinforced  concrete  piles  makes  an 
[48]  ,  <  -! 


REIX FORCED  CONCRETE  CONSTRUCTION 


REINFORCED     CONCRETE    WAREHOUSE    OF    THE    STANDARD    TABLE    OIL    CLOTH   COMPANY, AT 
YONKERS,  N.  Y       HENNEBIQUE  SYSTEM 


THIS  PICTURE  SHOWS  THE  USE  OF  CLINTON    ELECTRICALLY    WELDED    FABRIC     OX    THE    REIN- 
FORCED  CONCRETE   ROOF  OF  THE   DECAUVILLE    GARAGE,  NEW   YORK 

[49] 


REINFORCED  CONCRETE 

ideal  foundation  and  their  monolithic  nature  enables  them  to  resist  the 
stresses  of  unequal  settlement.  .  In  addition,  such  a  building  is  also  lighter 
than  one  of  regular  brick  work  or  masonry  which  is  another  advantage. 

Systems  of  Reinforcement 

The  astonishing  spread  of  reinforced  concrete  construction  has  natural- 
ly brought  about  a  corresponding  development  in  the  methods  of  reinforc- 
ing. In  the  following  pages  we  have  endeavored  to  outline  in  brief  the  im- 
portant features  of  a  number  of  reinforcing  systems  which  are  in  extensive 
use  to-day  in  reinforced  concrete  work. 

While  steel  in  small  sections  is  used  almost  entirely  for  the  reinforce- 
ment there  is  a  great  variety  in  the  shape  and  character  of  the  metal  em- 
ployed. For  the  flat  systems  some  form  of  netting  or  fabric  is  most 
commonly  used,  while  for  beams,  bars  or  cables  of  various  sections  are 
employed. 

In  some  instances  plain  round  or  square  bars  or  wires  are  used,  but 
practice  in  this  country  has  demonstrated  the  importance  of  the  shape  of 
the  reinforcement  being  such  that  it  will  offer  resistance  to  slipping  in  the 
concrete,  independent  of  the  adhesion  of  the  mortar. 

In  this  connection  Mr.  Edwin  Thatcher,  a  prominent  civil  engineer, 
states  that  "although  the  natural  adhesion  between  concrete  and  steel 
appears  to  be  very  great,  he  does  not  consider  it  wise  to  place  reliance  upon 
any  concrete  steel  construction,  but  provides  mechanical  connection  suffi- 
cient to  ensure  its  safety  in  case  the  adhesion  from  any  cause  amounts  to 
little  or  nothing," 

The  Kahn  System 

This  system,  which  is  being  advocated  by  the  Trussed  Concrete  Steel 
Co.,  of  Detroit,  Mich.,  embodies  the  use  of  what  is  known  as  the  Kahn 
trussed  steel  bar.  This  bar  is  rolled  of  a  diamond  section  with  projecting 
wings  on  either  side.  The  wings  are  slotted  off  along  the  edge  of  the  dia- 
mond for  certain  distances  and  are  bent  up  to  an  angle  of  about  forty-five 
degrees  to  form  the  reinforcements  resisting  the  shearing  stresses.  They 
are  consequently  rigidly  connected  to  the  main  bottom  bars. 

The  three  principal  advantages  claimed  for  the  employment  of  this 
form  of  reinforcement  are  : 

1.  The  reinforcement  in  the  vertical  plane  is  rigidly  attached  to  the 
main  horizontal  member  and  lies  in  such  a  direction  as  to  cross  at  right 
angles  the  lines  of  rupture. 

2.  The  design  of  the  diagonals  economizes  in  the  amount  of  metal  re- 
quired and  enables  same  to  be  placed  with  a  maximum  amount  of  speed  and 
economy. 

3.  Absolute  fireproofness  of  structures  is  the  result  because  this  rein- 
forcement does  not  depend  upon  the  lower  part  of  the  concrete,  which  is 
affected  by  fire. 

[50] 


REINFORCED  COXCRETH   CONSTRUCTION 


REINFORCED    CONCRETE    RESERVOIR    IN    COURSE    OF    CONSTRUCTION    FOR    THE    U.  S.    GOVERN- 
MENT AT   KEY   WEST.     EXPANDED    METAL  AND   KAHN   TRUSSED 
BARS  USED  AS   REINFORCEMENT 


FACTORY    RCOF    BUILT   IN    ACCORDANCE    WITH    THE    FERROINCLAVE    SYSTEM,— CORRUGATED 
METAL    WITH    CONCRETE    ABOVE    AND    BELOW 

[51] 


REINFORCED  CONCRETE 

The  warehouse  for  Farwell,  Ozmun,  Kirk  &  Co.,  at  St.  Paul,  Minn., 
which  is  stated  to  be  the  largest  reinforced  concrete  warehouse  in  the  United 
States,  was  reinforced  throughout  according  to  the  Kahn  system.  The 
entire  interior  construction,  including  such  structural  members  as  column 
footings,  wall  footings,  columns,  girders,  beams  and  floor  slabs  is  of  rein- 
forced concrete.  The  building  is  nine  stories  in  height  and  the  actual  floor 
area  is  approximately  450,000  square  feet. 

The  floors  are  designed  to  carry  the  heaviest  hardware  warehouse  load- 
ings, which  would  be  equivalent  to  500  pounds  per  square  foot  over  the  en- 
tire area  of  the  floor. 

Whole  panels  have  been  tested  up  to  1,500  pounds  per  square  foot  with- 
out any  appreciable  effect  on  the  floor  construction.  This  is  a  remarkable 
load  and  was  obtained  by  piling  pig  iron  as  densely  as  possible  to  a  height 
of  eight  feet  on  one  complete  panel.  Were  this  load  to  be  placed  upon  a 
truck  it  would  require  forty  horses  to  haul  it  away.  The  pig  iron  resting  on 
the  floor  stood  two  feet  higher  than  the  head  of  a  six  foot  man.  It  was  al- 
most impossible  to  get  a  greater  load  on  the  panel  as  there  was  almost  solid 
iron  from  the  floor  to  the  ceiling. 

The  Clinton  System 

A  reinforcing  for  concrete  construction  of  all  kinds  which  is  being  ex- 
tensively used  in  this  country  is  the  electrically  welded  fabric  manufactured 
by  the  Clinton  Wire  Cloth  Company,  of  Clinton,  Mass.  The  late  Frank  E. 
Kidder  stated  that  from  a  theoretical  standpoint  at  least  this  fabric  would 
seem  to  oifer  the  ideal  reinforcement  for  slab  construction,  as  the  carrying 
wires  may  be  varied  both  in  size  and  spacing  to  give  the  necessary  area  for 
any  given  weight  and  span.  The  distributing  or  cross  wires  may  like- 
wise be  varied  in  the  same  way.  The  direction  of  the  wires  coincides 
with  the  line  of  stress  so  that  there  is  no  tendency  to  distort  the  rect- 
angle of  the  mesh. 

As  this  fabric  comes  in  3oo-foot  rolls  it  can,  in  a  building  say,  for 
instance,  200  feet  long,  be  secured  at  the  front  or  rear  and  carried  through 
the  entire  distance  without  a  break.  Owing  to  the  continuous  bond  the 
reinforcing  is  equally  strong  at  all  points  and  the  reinforcing  members  are 
exactly  spaced  2,  3  or  4  inches  apart  as  the  case  may  be.  This  spacing?  is 
exact;  it  is  established  by  machinery  and  is  not  subject  to  the  care- 
lessness of  employees. 

Due  to  the  continuous  bond  secured  by  the  Clinton  fabric  no  entire 
collapse  of  any  arch  erected  with  it  can  occur,  unless  the  weight  imposed  on 
the  arch  is  sufficient  to  strain  and  break  all  of  the  wires.  In  the  Produce  Ex- 
change National  Bank,  New  York,  arches  14  feet  8  inches  center  to  center 
of  beams  were  put  in  place  and  some  of  them  not  being  protected  were  al- 
lowed to  freeze.  These  arches  were  reinforced  with  the  Clinton  fabric. 
They  subsequently  thawed  out,  froze  and  thawed  out  again.  The  result  was 

[5*1 


REIXFORCED  CONCRETE  CONSTRUCTION 

that  although  the  concrete  was  rendered  worthless  and  despite  the  fact 
that  the  reinforcement  was  carrying  not  only  the  weight  of  the  damaged  con- 
crete but  also  the  weight  of  all  materials  moved  through  the  rooms,  work- 
men, machinery,  etc.,  and  was  withstanding  the  rough  usage  to  which 
buildings  at  that  stage  are  subjected,  each  of  the  arches  remained  intact  due 
to  the  continuous  bond  of  high  tension  steel  wire  extending  throughout 
the  entire  width  of  the  arch  and  securely  fastened  around  the  outer  flanges 
of  the  I-beam. 

The  Unit  System 

In  the  Unit  system,  which  is  controlled  by  the  Unit  Concrete  Steel 
Frame  Company,  of  Philadelphia,  all  of  the  metallic  reinforcement  for 
each  beam  or  girder  is  made  into  a  single  unit  and  placed  as  a  unit  in 
the  form.  This  is  accomplished  by  having  both  the  straight  and  camber 
bars  fastened  together  by  stirrups  and  clamps,  so  that  each  tension 
and  shear  member  is  rigidly  held  in  its  proper  position.  This  precludes 
the  possibility  of  one  or  more  members  being  omitted  or  incorrectly 
placed  by  workmen  at  the  building,  and  affords  opportunity  for  inspec- 
tion prior  to  use.  Its  exact  position  in  the  form  is  fixed  and  rigidly 
secured  by  means  of  what  is  called  the  Unit  socket,  made  of  cast  steel 
of  ij  or  2  inches  in  height,  as  may  be  required  by  specifications  for 
fireproofing.  This  socket  is  tapped  for  a  f-inch  bolt,  and  is  bolted  into 
the  bottom  of  the  mold.  A  f-inch  threaded  stud  projects  from  the  top 
of  the  socket.  Four  or  more  of  these  sockets  are  placed  in  the  mold, 
usually  four  or  five  feet  apart,  and  the  girder  frame  is  then  set  upon 
them  in  a  manner  to  permit  of  the  stud  protruding  between  the  main 
bars  of  the  girder  frame.  The  girder  frame  is  then  secured  and  rigidly 
held  by  a  washer  and  nut  screwed  down  on  this  stud  over  the  frame, 
and  inspected  as  to  their  accuracy  before  being  covered  by  the  concrete. 
The  sockets  are  afferward  utilized,  in  many  instances,  for  the  support- 
ing of  shafting,  motors,  piping  or  other  overhead  fixtures. 

Another  feature  of  this  system  is  the  punch  stirrup,  permitting 
and  requiring  the  lacing  of  the  slab  rods  through  the  eyes  of  'the  stirrup, 
thus  making  a  metallic  connection  between  the  slab  and  the  beam  or 
girder. 

The  advantages  claimed  for  this  system  are  absolute  accuracy  in 
the  placing  of  the  reinforcing  material ;  the  ease  with  which  it  can  be 
inspected  and  errors,  if  any,  detected  and  corrected  before  concreting; 
the  impossibility  of  omitting  any  tension  or  shear  member ;  the  addi- 
tional strength  secured  by  binding  the  slab  concrete  to  the  beam  con- 
crete by  means  of  lacing  of  the  slab  reinforcement  through  the  stirrups, 
The  girder  frames  may  thus  be  set  in  advance  of  the  concrete  work, 
and  the  provision  for  shafting  or  other  overhead  fixtures. 

[53] 


REINFORCED  CONCRETE 

The  Hinchman-Renton  System 

While  plain  iron  rods  have  never  been  known  to  slide  or  slip  in  concrete 
yet  on  account  of  the  possibility  that  the  sliding  resistance  along  the  em- 
bedded steel  will  decrease  in  time  under  frequently  repeated  loads,  Amer- 
ican engineers  have  deemed  it  wise  to  use  the  reinforcing  steel  in  such 
shape  that  sliding  in  the  concrete  will  be  impossible  without  tearing 
and  crushing. 

In  seeing  for  material  that  would  satisfactorily  supply  the  tensile 
strength  required  by  floor  slabs  it  occurred  to  Mr.  J.  B.  Hinchman  of  the 
Hinchman-Renton  Company,  Denver,  Colorado,  that  ordinary  barbed  wire 
would  afford  the  necessary  reinforcement.  In  addition  barbed  wire 
is  also  inexpensive  and  readily  obtained  in  any  quantity. 

Test  slabs  were  therefore  made  by  the  above  mentioned  company  on 
the  Monier  principle  by  using  the  barbed  wire  in  place  of  plain  rods  and 
wires.  These  tests  proved  so  satisfactory  that  the  company  decided  to  use 
barbed  wire  in  their  future  work  and  applied  and  secured  patents  on  its  ap- 
plication in  concrete  floor  construction.  Excellent  results  have  been  obtain- 
ed with  this  method  of  reinforcement. 

For  concrete  beams  of  long  spans  a  greater  sectional  area  of  the 
material  is  required  than  can  be  obtained  with  barbed  wire.  Hence 
where  the  span  exceeds  eight  feet  the  Hinchman-Renton  Company  has 
adopted  a  punched  channel  bar  as  the  reinforcement  member. 

Owing  to  the  great  surface  of  these  channels  in  proportion  to  their 
weight,  and  the  perfect  key  obtained  with  the  concrete  they  have  been  found 
to  possess  superior  qualities.  In  addition  they  are  economical  and  can 
be  readily  obtained  in  any  quantity  and  of  various  dimensions.  By  the  use 
of  this  tension  bar,  with  cross  ties  of  barbed  wire,  it  is  practicable  to  con- 
struct floors  having  a  clear  span  of  20  feet  and  to  erect  a  monolithic  concrete 
structure  without  the  use  of  steel  floor  beams. 

A  test  slab  41-4  inches  thick,  40  inches  wide  and  with  a  clear  span  of  6 
feet,  reinforced  according  to  the  system  advocated  by  the  Hinchman-Ren- 
ton Company  showed  a  carrying  capacity  of  1,300  pounds  or  650  pounds  a  sq. 
ft.  with  apparent  safety.  This  slab  was  formed  in  a  box  and  was  set  loose  on 
top  of  the  steel  beam.  Experience  has  shown  that  when  built  in  place,  as 
in  actual  construction,  the  carrying  capacity  is  greatly  enhanced. 

A  similar  slab  made  at  the  same  time  and  of  exactly  the  same  composi- 
tion but  without  the  barbed  wire,  failed  without  warning  under  a  load  of 
only  28  pounds  per  square  foot,  showing  that  there  is  perfect  adhesion  be- 
tween the  concrete  and  the  barbed  wire  tension  members. 

It  is  a  well  known  principle  of  engineering  that  a  continuous  slab  sup- 
ported at  the  four  sides  will  support  a  much  greater  load  than  if  divided 
into  separate  beams  without  connection  at  the  sides.  Reinforced  concrete 
floors  in  building  have  time  and  again  shown  a  strength  that  would  appear 

[54] 


REINFORCED  CONCRETE  CONSTRUCTION 


THE  CRANDALL  TWISTED  STEEL  BARS,  SHOWING  THE  METHOD  OF  USING  THEM  IN  REINFORCED 
CONCRETE  CONSTRUCTION  WORK 

incredible  if  the  fact  were  overlooked  that  the  floor  is  monolithic  over  this 
channel  and  that  the  strength  radiates  in  all  directions  from  the  points  of 
support. 

The  Hinchman-Renton  Co.  are  prepared  to  construct  and  guarantee 
fireproofing  by  their  system  which  shall  sustain  a  universally  distributed  load 
of  1,000  pounds  per  square  foot  and  over  with  a  clear  span  of  six  feet. 

The  Columbian  System 

This  is  a  flat  concrete  system  with  ribbed  steel  tension  members. 
Rolled  joists  are  used  for  beams,  embedded  in  concrete,  the  double  cross 

[551 


REINFORCED  CONCRETE 

floor  reinforcements  being  held  in  place  by  flat  iron  inverted  stirrups  placed 
over  the  top  flanges  of  the  joists.  The  vertical  ledge  of  the  stirrups  are 
slotted  out  in  the  shape  of  double  cross  sections  and  the  floor  bars  are 
housed  in  the  slotted  holes. 

The  bottom  flanges  and  the  roof  joists  are  especially  protected  against 
fire  by  troughs  of  concrete,  in  the  sides  of  which  pieces  of  hoop  iron  are  im- 
bedded with  their  ends  projecting.  These  are  clipped  around  the  flange  of 
the  joists  and  hold  the  joists  against  the  bottom  surface.  The  hollows  thus 
formed  leave  an  air  space  between  the  concrete  and  the  under  side  of  the 
flanges.  All  reinforcing  steel,  connected  angles  and  stirrups  are  made  from 
mild  steel  of  either  open  hearth  or  Bessemer  process,  having  an  ultimate 
strength  of  60,000  to  70,000  pounds  per  square  inch  and  an  elastic 
limit  of  not  less  than  one-half  the  ultimate  strength.  All  material  is  care- 
fully tested  according  to  standard  methods  before  being  accepted  for  use. 

An  interesting  instance  of  construction  involving  the  use  of  the  Colum- 
bian system  of  reinforcement  was  furnished  in  the  case  of  the  Mess  Hall  of 
the  Midshipmen's  Quarters  at  the  U.  S.  Naval  Academy  at  Amiapolis.  In 
front  of  the  Mess  Hall  is  located  the  drill  ground,  and  after  the  hall  had 
been  designed  it  was  decided  to  arrange  a  series  of  terraces  on  the  roof  in 
order  to  furnish  seating  capacity  for  spectators  watching  the  evolutions 
of  the  cadets.  The  Mess  Hall  is  75  x  375  feet  inside  with  two  lines  of  rein- 
forced concrete  columns  25  feet  center  to  center,  each  way,  dividing  the  en- 
tire area  into  25-foot  squares.  The  roof  is  made  up  of  groined  arches  of  25 
feet  6  1-2  inch  radius.  The  crux  of  the  problem  lay  in  the  fact 
that  the  outside  walls  would  not  stand  any  thrust  and  it  was  there- 
fore necessary  to  design  a  construction  that  exerted  only  a  vertical  stress 
upward  on  the  supports.  The  problem  was  solved  by  building  the  whole 
roof  as  a  cantilever.  The  section  between  the  two  inner  rows  of  columns 
was  cast  solid  with  a  joint  in  the  center,  the  outside  ends  of  the  beam  being 
supported  by  the  joint  and  outside  wall. 

The  Hennebique  System 

This  system,  which  is  one  of  the  best  known  and  most  extensively  used 
in  Europe,  was  brought  out  in  1892  by  M.  Hennebique,  who  was  one  of 
the  first  to  introduce  the  reinforced  concrete  beam  and  is  sometimes  mis- 
takenly designated  as  its  original  inventor. 

The  floors  according  to  the  Hennebique  system  are  formed  in  several 
ways,  the  most  commonly  employed  being  the  flat  single  floor  with  exposed 
beams.  The  floor  rods  are  in  two  series,  one  bent  up  to  pass  over  the  support 
near  the  upper  surface  of  the  slab  and  the  other  set  straight  throughout  and 
embedded  near  the  lower  surface.  The  rods  are  placed  alternately,  one  straight 
and  the  next  bent  up  over  the  supports.  The  hoop  iron  stirrups  which  are  a 
feature  of  this  svstem  are  placed  near  the  supports  to  resist  the  shearing 

[56] 


REINFORCED  CONCRETE  CONSTRUCTION 


ii 

II 


I 


y 


[57] 


REINFORCED  CONCRETE 


METHOD    OF    TESTING     THE    STRENGTH     OF     REINFORCED     CONCRETE    FLOORS    CONSTRUCTED 

ON    THE     UNIT   SYSTEM 


TEST    LOAD    ON    A    SLAB    7^    INCHES    THICK,  WITH    il/>   INCH    STRIP    PILING 
(  See  page  336  for  description  ) 


[581 


REINFORCED  CONCRETE  CONSTRUCTION 

stresses.  These  stirrups  pass  under  the  rods,  their  extremities  being  slightly 
bent  and  terminating  near  the  upper  surface  of  the  concrete. 

Beams  are  reinforced  in  the  same  manner  as  slabs  with  straight  bent- 
up  rods,  but  in  this  case  the  straight  rods  are  placed  near  the  bottom  sur- 
face and  the  bent  rods  above  them.  The  ends  of  the  rods  are  carried  over 
the  supports  and  some  distance  into  the  adjoining  beam  or  wall.  The  main 
stirrups  of  the  beams  are  spaced  further  and  further  apart  from  the  sup- 
port toward  the  center  of  the  span  as  the  shearing  stress  diminish  in  a  like 
manner;  a  further  series  of  short  stirrups  is  placed  over  ends  of  the  bent-up 
rods  to  firmly  secure  them  to  the  concrete.  When  the  depth  of  the  beam  is 
too  small  to  obtain  the  necessary  compressive  resistance  from  the  concrete 
alone  a  further  series  of  straight  rods  is  employed  near  the  upper  surface. 

The  beams  and  floor  slabs  are  monolithic  and  in  consequence  the 
beams  are  designed  as  being  of  T-section.  When  these  are  freely  supported 
the  bent-up  rods  are  omitted. 

The  walls  in  the  Hennebique  system,  when  the  pressure  may  occur 
on  both  sides  are  reinforced  with  two  series  of  vertical  rods,  one  near  each 
face.  Each  set  is  tied  to  the  opposite  face  with  stirrups,  longitudinal  rods 
being  placed  in  the  center  of  the  rod.  If  the  pressure  will  be  only  exerted 
on  one  side  of  the  wall  the  vertical  rods  will  be  placed  only  on  its  face. 

Ferroinclave 

Sheets  of  thin  steel  are  corrugated  so  as  to  form  dove-tail  grooves  have 
been  used  by  a  number  of  firms  as  a  reinforcement  and  centering  for  con- 
crete steel,  the  dove-tailing  serving  to  unite  the  sheets  to  the  concrete. 
Under  the  name  of  Ferroinclave  the  Brown  Hoisting  Machinery  Company 
of  Cleveland,  have  patented  a  tapered  corrugation  which  is  small  enough 
to  hold  mortar  and  hence  can  be  plastered  on  the  under  side. 

This  material  is  principally  used  in  the  construction  of  fire  resisting 
roofing,  siding,  flooring,  etc.,  for  factory  buildings,  power  plants  and  the 
like.  After  being  secured  in  place  it  is  always  coated  on  both  sides  with 
Portland  cement  mortar. 

Ferroinclave  is  generally  made  of  No.  24  U.  S.  gauge  box  and  an- 
nealled  sheet  steel.  Each  sheet  is  accurately  crimped  by  special  machinery 
into  the  dove-tail  section.  The  corrugations  are  a  half  inch  in  depth  of 
height  and  are  two  inches  center  to  center.  They  are  made  wider  at  one 
end  of  each  sheet  than  at  the  other  so  that  sheets  may  be  shingled  or  fit  end- 
wise into  each  other.  The  principal  advantage  in  the  use  of  corrugated 
sheets  for  floor  construction  lies  in  their  ability  to  sustain  the  concrete 
(with  moderate  spans)  before  it  was  set,  thus  saving  the  cost  of  centering 
and  the  time  required  in  putting  it  in  place. 

For  roofs,  Ferroinclave  would  seem  to  be  an  exceedingly  light  and 
cheap  form  of  construction  as  the  total  thickness  need  not  exceed  i  1-4 

[59] 


REINFORCED  CONCRETE 

inches  and  it  only  requires  an  asphaltic  paint  over  the  same  to  make  the  roof 
watertight. 

With  a  good  coat  of  hard  plaster  or  gauge  mortar  on  the  under  side 
the  iron  will  not  be  affected  by  heat  until  a  considerable  time  has  elapsed, 
and  even  if  the  mortar  on  the  under  side  should  be  more  or  less  dislodged 
by  the  stream  of  water  it  can  be  replaced  at  a  very  slight  expense.  Another 
advantage  of  Ferroinclave  for  roofs  is  that  the  building  can  be  covered  and 
made  watertight  in  the  most  severe  winter  weather  and  the  cement  applied 
during  the  following  spring. 

The  Turner  Mushroom  System 

The  promoter  of  this  system,  Mr.  C.  A.  P.  Turner,  claims  that  in  ware- 
house work  it  is  perfectly  feasible  to  put  up  a  building  with  columns  at  16 
foot  centers  with  a  floor  of  7  1-2  in.  rough  slabs,  using  no  ribs  at  all,  and 
test  it  with  800  lb.  per  sq.  ft.  without  injury  to  the  construction.  Further- 
more, he  claims  that  it  can  be  put  up  at  less  cost  without  the  ribs,  and  will 
require  less  metal,  as  the  load  will  travel  more  directly  to  the  supports, 
instead  of  around  a  corner,  as  in  the  case  where  beams  are  used.  The 
method  of  construction  which  he  employs  is  shown  in  the  accompanying 
illustration/ 

The  small  bend  in  the  truss  gives  them  an  anchorage  in  the  concrete, 
which,  from  Mr.  Turner's  experience  appears  to  discount  any  form  of 
wicked-section  mechanical  bond  yet  invented.  In  one  instance,  iad  work, 
on  the  part  of  an  incompetent  contractor,  on  a  footing  gave  Mr.  Turner 
an  opportunity  of  judging  the  amount  of  distortion,  a  connection  of  this 
character  would  stand.  He  found  that  it  would  stand,  if  anything,  as  great 
an  amount  of  distortion,  without  material  injury,  as  could  be  expected  from 
a  structural  steel  frame  with  standard  riveted  connections  of  the  web  of 
the  beams  to  the  columns.  Such  reinforcement  is  more  satisfactory  from  the 
standpoint  of  resistance  to  lateral  or  vibratory  forces. 

The  Crandall  System 

An  interesting  application  of  reinforced  concrete  was  that  recently 
employed  in  the  construction  of  a  slope  wall  along  the  Allegheny  River 
at  Warren,  Pa.,  for  the  purpose  of  protecting  the  low  land  adjacent 
to  the  river  and  the  important  manufacturing  establishments  at  that 
point  from  the  effects  of  floods  which  are  of  frequent  occurance  in  that 
locality.  A  levee,  constructed  a  number  of  years  ago,  had  proved  in- 
adequate, and  the  question  of  adequately  protecting  this  part  of  the 
city  was  therefore  a  serious  and  important  one,  calling  for  the  outlay 
of  a  large  sum  of  money. 

Mr.  D.  F.  A.  Wheclock,  city  engineer  of  Warren,  was  employed  to 
solve  the  problem,  prepare  plans,  etc.  and  carry  out  the  scheme.       His 
aim  was  to  afford  perfect  and  permanent  protection  at  the  least  possible 
outlay. 
[60] 


REINFORCED  CONCRETE  CONSTRUCTION 


QjH- 


OX 

oo 


w£ 
*'£ 


[6iJ 


REINFORCED  CONCRETE 

Breakwaters,  stone  retaining  walls,  rip-rapping  and  reinforced  con- 
crete were  considered,  and  plans  and  specifications  prepared  for  the 
different  methods  of  construction.  The  plans  with  reference  to  the 
construction  of  breakwaters  called  for  such  an  enormous  expense  that 
they  were  abandoned ;  those  for  the  retaining  walls  were  aban- 
doned on  account  of  the  expense  and  also  the  improbable  permanence 
and  durability  of  the  work.  Bids  were  asked  for  on  two  plans,  one 
for  thoroughly  rip-rapping  the  bank  of  the  river  against  the  levee, 
which  was  to  be  repaired  and  extended  for  some  distance,  and  the 
other  for  a  reinforced  concrete  wall  to  be  built  on  a  slope  of  one  to  one 
and  which  would  not  require  additions  to  the  remains  of  the  levee. 

When  the  bids  were  opened,  it  was  found  that  the  reinforced  con- 
crete wall  could  be  constructed  for  about  80%  of  the  cost  of  rip-rapping 
and  repairing  the  old  wall.  The  successful  bid  called  for  the  use 
of  Crandall  bars  made  of  high  carbon  twisted  steel,  the  concrete  to  be 
eight  inches  thick,  to  withstand  a  shock  three  times  greater  than  that 
which  rip-rapping  would  sustain,  with  a  thickness  of  from  fifteen  to 
eighteen  inches.  The  Crandall  bars  were  accepted  after  a  series  of 
thorough  and  exhaustive  tests. 

In  the  construction  of  the  wall,  Crandall  bars  were  placed  six 
inches  from  the  face  and  two  inches  from  the  back  of  the  wall  and  one 
foot  apart  horizontally  for  the  whole  length  of  the  wall,  and  also  one 
foot  apart  vertically  all  along  the  slope  of  the  wall.  The  bars  used 
were  of  -J-inch  twisted  steel.  As  the  use  of  reinforced  concrete  in 
that  section  of  Pennsylvania  is  rather  novel,  the  construction  of  the 
wall  naturally  excited  considerable  interest  among  engineers,  contractors 
and  others  interested  in  that  class  of  work,  and  has  been  pro- 
nounced one  of  the  most  successful  engineering  feats  in  that  section 
of  the  state. 

The  wall  is  20  feet  high  and  constructed  in  sections  separated  by 
sand  joints  every  fifteen  feet,  the  reinforcing  bars  extending  through 
the  sand  joint  into  the  next  section  for  a  distance  of  twelve  inches. 
This  was  done  in  order  to  protect  the  wall  against  cracking;  by  lapping 
the  bars  over  the  sand  joints,  the  wall  was  protected  at  these  points 
against  accidents.  The  concrete  was  mixed  in  the  proportion  of  one 
part  cement  to  six  parts  of  gravel  and  sand  so  combined  as  to  fill  all 
the  voids. 

The  bars  employed  in  this  work  were  manufactured  by  Charles  D. 
Crandall,  of  Warren,  Pa. 

Early  American  Patents. 

The  first  patent  to  be  issued  in  connection  with  reinforced  concrete 
construction  in  the  United  states  was  that  granted  in  1878  to  Thaddeus 
Hyatt  on  a  combination  of  iron  and  concrete.  This  patent  virtually  cov- 
[62] 


REINFORCED   CONCRETE   CONSTRUCTION 


\    co-FOOT    SPAN     SHOWING    THE    USE     OF    THE     RANSOME     TWISTEDJ  BARS    FOR    REINFORCE- 
MENT   OF' CONCRETE    FLOORS    AT    THE    RIDING    AND    DRIVING    CLUB,    BROOKLYN 


[63] 


REINFORCED  CONCRETE 

ered  all  combinations  of  steel  and  concrete  in  which  the  steel  is  provided 
with  obstructions  to  sliding.  However,  as  a  principle  cannot  be  patented, 
Hyatt's  patent  covered  only  the  special  form  of  reinforcement  described  by 
him.  This  left  the  field  still  open  for  other  shapes. 

Hyatt,  among  other  things,  thoroughly  realized  that  the  combination 
of  iron  or  steel  with  concrete  would  be  unsuccessful  unless  the  coefficient 
of  expansion  was  the  same.  Therefore,  in  order  to  thoroughly  satisfy 
himself  on  this  score,  he  conducted  a  series  of  experiments  to  determine 
the  expansion  of  the  material  separately  and  also  when  the  reinforcement 
was  imbedded  in  the  concrete.  This  experiment  showed  the  lineal  expan- 
sion of  concrete  to  be  .00137  for  180  degrees  as  compared  with  .00140 
for  wrought  iron.  He  furthermore  exposed  blocks  of  concrete  containing 
bars  of  iron  to  the  red  heat  of  a  furnace  for  six  hours  and  found  them 
to  be  entirely  sound  when  taken  out,  demonstrating  that  the  relation  of 
the  two  materials  is  not  affected  by  expansion  or  construction. 

The  danger  of  employing  a  combination  of  materials  whose  co-efficient 
of  expansion  is  unequal  was  illustrated  in  a  striking  manner  during  the 
big  conflagration  at  Baltimore.  In  a  number  of  buildings,  terra  cotta  was 
enclosed  within  steel  members.  Under  the  tremendous  heat  to  which 
these  materials  were  subjected,  the  terra  cotta  expanded  twice  as  much 
as  the  steel,  ultimately  causing  the  collapse  of  the  floors  and  partitions 
erected  of  these  materials.  Reinforced  concrete  walls  and  partitions,  how- 
ever, were  found  to  be  in  a  practically  perfect  condition,  despite  the 
tremendous  temperature  to  which  this  construction  has  been  subjected. 

Shortly  before  the  granting  of  Hyatt's  patent,  a  reinforced  concrete 
building — the  first  in  this  country — had  been  erected.  This  was  the  resi- 
dence of  W.  E.  Ward,  at  Port  Chester,  N.  Y.,  shown  in  the  September 
issue  of  CEMENT  AGE,  which  was  erected  in  1875,  and  is  to-day  in  as 
sound  and  unscathed  a  condition  as  it  was  thirty-one  years  ago.  This 
building  is  constructed  entirely  of  concrete,  reinforced  with  light  iron 
beams  and  rods,  the  only  wood  being  in  the  window  sashes  and  door 
frames,  mop-boards  and  stair-rails.  Thus,  everything  combustible  is 
excluded  from  the  main  construction. 

The  Ransome  System 

P.  H.  Jackson,  a  civil  engineer  of  San  Francisco,  was  among  the  first 
to  make  practical  use  of  Hyatt's  patent  in  connection  with  reintorced 
concrete  construction  in  1877  and  disseminated  a  great  deal  of  information 
on  concrete  construction  in  general,  and  reinforced  concrete  in  particular. 
At  about  the  same  time,  Ernest  L.  Ransome,  the  pioneer  of  reinforced 
concrete  constrcution  in  the  United  States,  who  had  been  very  successful 
as  a  designer  and  builder  of  concrete  structures  in  San  Francisco, 
conceived  the  idea  of  using  square  bars  of  iron  or  steel  twisted  their  entire 
length  for  the  reinforcing  of  concrete,  patenting  this  improvement  in  1884. 

[64] 


REIXFORCED    COXCRETE    CONSTRUCTION 


p 


O  t_, 


PQ  < 
OPQ 

z°* 
SUM 

Q     a 

-       oi 


Si 


[65] 


REINFORCED  CONCRETE 

The  bars  are  twisted  cold  with  a  varied  number  of  twists  per  yard. 
The  effect  of  this  treatment  is  to  greatly  increase  the  ultimate  strength 
and  elastic  limit,  and  preventing  any  tendency  toward  sliding  in  the 
concrete.  Beams  and  floor  slabs  are  constructed  together  and  are  fre- 
quently very  similar  to  those  made  according  to  the  Hennebique  system, 
except  that  square  twisted  bars  are  used  for  the  reinforcement  in  the 
vertical  plane. 

Under  Mr.  Ransome's  direction,  a  number  of  buildings  were  con- 
structed of  reinforced  concrete  in  California,  despite  the  dire  prophecies 
that  that  form  of  construction  was  not  adapted  to  a  country  subject  to 
seismic  disturbances.  These  prophecies  were,  however,  glowingly  dis- 
proved during  the  recent  earthquake ;  while  brick  and  other  stone  struc- 
tures in  their  immediate  vicinity  were  wrecked,  the  reinforced  concrete 
buildings  erected  by  Ransome  passed  through  the  ordeal  unscathed,  prov- 
ing that  for  an  earthquake  country,  reinforced  concrete  is  the  safest 
structural  material  which  can  be  employed. 

The  only  event  which  could  bring  about  the  entire  collapse  of  a 
properly  designed  and  constructed  reinforced  concrete  building,  would  be 
the  giving  way  of  the  ground  beneath  it.  Even  in  such  a  case,  unless  the 
flexing  strain  became  unusually  severe,  the  building,  due  to  its  monolithic 
nature,  would  be  very  likely  to  sustain  only  slight  damage.  Furthermore, 
-the  conflagration  usually  accompanying  earthquakes  would  find  but  little 
to  attack  in  a  building  of  this  type,  as  was  shown  to  be  the  case  at  San 
Francisco. 

It  is  mainly  due  to  Ransome's  missionary  work  that  reinforced  con- 
crete construction  has  reached  its  present  commanding  position  in  building- 
construction.  Through  communications  to  the  technical  press,  the  reading 
of  papers  before  engineering  societies,  lecturing  before  architects  and 
engineers,  he  kept  up  an  active  propaganda  on  the  subject  and  paved  the 
way  for  the  widespread  introduction  of  this  new  form  of  construction. 
An  instructive  index  of  the  effect  of  this  constant  hammering  away  is 
offered  by  the  figures  showing  the  growth  of  the  production  of  Portland 
cement  coincident  with  the  spread  of  reinforced  concrete  construction. 
While  in  1890,  when  Ransome  began  his  crusade,  the  production  was  only 
300,000  barrels,  it  had  increased  to  36,000,000  barrels  in  1905,  one  of  the 
most  remarkable  instances  of  results  of  persistency  upon  an  industry  in 
recent  times. 

The  first  application  of  reinforced  concrete  to  factory  and  mill  con- 
struction on  a  large  scale  was  in  the  factory  of  the  Pacific  Coast  Borax  Co.. 
at  Bayonne,  N.  J.,  which  was  erected  by  Ransome  in  1898.  The  fireproof 
qualities  of  the  construction  were  demonstrated  by  the  severe  conflagration 
which  it  was  subjected  to  some  time  ago,  during  which  it  sustained  com- 
paratively little  damage,  the  high  temperatures,  increased  as  they  were 
[66] 


REIXl'ORCED   CONCRETE   CONSTRUCTION 


REINFORCED    CONCRETE    FACTORY    OF    THE    EASTWOOD    MACHINE    SHOP,    NEWARK,   N.    J. 
REINFORCED    WITH    EXPANDED    METAL 


ROOF    OK    THE    NEWARK    WAREHOUSE    CO  ,    NEWARK,    N.     I.,    REINFORCED    WITH 
EXPANDED    METAL 


[67] 


REIXFORCED  COXCRETE 

by  the  fumes  of  acid,  would  have  completely  wrecked  any  other  type  of 
structure. 

The  Expanded  Metal  System 

Another  pioneer  in  the  development  of  reinforced  concrete  con- 
struction in  the  United  States  was  John  F.  Golding,  well  known  as  the 
inventor  of  expanded  metal.  He  was  induced  to  experiment  with  the 
latter  as  a  reinforcement  for  concrete  slabs,  his  experiment  proving  so 
successful  that  expanded  metal  construction  has  come  rapidly  into  great 
prominence. 

Expanded  metal  is  made  from  mild  steel,  having  an  ultimate  resistance 
of  48,000  pounds  per  square  inch  and  an  elongation  of  21  per  cent,  in  a 
length  of  8  inches.  It  is  manufactured  from  flat  plates  of  thickness  vary- 
ing from  %  to  about  T/s  of  an  inch,  and  when  expanded,  the  usual  meshes 
are  from  6  inches  to  3  inches  in  width.  The  operation  of  making  it 
consists  in  placing  the  sheets  vertically,  resting  on  their  edges.  They  are 
then  slotted  and  pulled  out  at  one  operation.  After  being  slotted,  they  are 
drawn  out  laterally  so  that  the  width  of  the  finished  sheet  is  in  reality  pro- 
duced from  the  height  of  the  original  plate  when  placed  with  its  edge 
downward.  The  expansion  effect  varies  from  about  6  to  12  times  the 
original  width  of  the  plate.  However,  no  alteration  is  made  in  the  length, 
the  strands  being  consequently  somewhat  stretched.  A  portion  is  left  uncut, 
thereby  forming  a  strong  "selvedge"  edge.  It  has  been  found  that  the 
ultimate  strength  is  increased  from  48,000  to  about  63,000  pounds  per 
square  inch  through  the  operation  of  expanding.  Expanded  metal  is 
mainly  used  for  slab  construction,  although  in  a  few  instances,  it  has  also 
been  used  in  the  construction  of  beams. 

The  Cummings  System 

The  characteristic  feature  of  this  system,  which  is  being  advocated 
by  the  Cummings  Structural  Concrete  Co.,  of  Pittsburg,  is  the  use  of  plain 
commercial  steel  shapes  for  reinforcement.  As  this  steel  requires  no 
special  molding  or  rolling,  and  can  be  readily  procured  out  of  stock,  the 
cost  of  the  reinforcement  is  naturally  reduced  to  a  minimum.  By  the  use 
of  a  patented  system  of  bars  looped  at  the  ends,  a  perfect  bond  is  provided 
with  the  concrete,  without  increasing  the  weight  of  steel  and  forming  a 
structure  secure  against  vibration  and  impact.  This  would  seem  to  make 
this  system  particularly  desirable  for  use  in  factories  containing  heavyr 
vibrating  machinery. 

The  loop  bars  for  beams  are  made  by  bending  and  welding  round  bars 
into  long  rectangular  frames.  The  ends  of  the  frames  are  bent  up  to  resist 
shearing  stresses  but  the  straight  part  of  the  frame  remains  at  the  bottom 
of  the  beam  to  take  its  proportional  share  of  the  bending  movement.  The 
bent-up  ends  form  a  looped  anchorage  by  which  the  steel  is  self-supporting. 
At  the  same  time,  it  cannot  be  disarranged  while  the  concrete  is  being- 
[68] 


REINFORCED  CONCRETE  CONSTRUCTION 

placed.  As  the  shearing  reinforcement  forms  a  part  of  the  longitudinal 
bars,  it  can  be  neither  displaced  nor  omitted. 

The  bars  of  a  beam  are  placed  in  two  layers  with  what  is  known  as 
the  Cummings  chair  between  them.  The  bottom  layer  of  the  bars  passes 
up  between  the  members  of  the  top  layer.  The  sizes  of  these  bars  range 
from  ^  to  ^4  of  an  inch  in  diameter. 

The  chair  is  stamped  from  sheet  or  bond  steel  having  regular  pro- 
jections which  are  bent  up  to  space  the  reinforcing  bars  and  down  to  hold 
them  in  position.  The  projections  are  adjusted  before  the  chairs  are 
placed  in  the  materials  and  the  steel  reinforcement  is  then  fixed  in  position. 
Being  entirely  imbedded  in  the  concrete,  the  chair  is  not  seen  when  the 
mold  is  removed.  The  essential  feature  of  this  device  is  that  it  insures 
accurate  spacing  and  fixing  of  the  reinforcing  steel  in  its  position. 


[69] 


REINFORCED  CONCRETE 


>   h 


[70] 


AN    EXAMPLE    OF    A    BRICK    AND    STONE    VENEER    ON    A    REINFORCED    CONCRETE     BUILDING; 
THE    BILGRAM    MACHINE    SHOP,    PHILADELPHIA 

CONCRETE    IN    FACTORY 
CONSTRUCTION 

The  demand  for  concrete  industrial  plants  is  rapidly 
increasing.      In  this  article  are  shown  some  ex- 
amples of  modern  factories,   with  a  general 
review   of  the  principles  oj   construction 

By 
£.  A.  Trego 

AMONG  many  building  types  to  which  concrete  has  been  applied, 
the  modern  factory  stands  as  a  conspicuous  example  of  its  worth. 
Concrete   is    peculiarly    adapted   to   buildings    of    this    character. 
Under  the   general   term  economy   mav  be  embraced   its   almost 
countless  advantages.    The  latter  include  fireproof  qualities  and  durability 
as  well  as  cheap,  but  none  the  less  substantial,  construction.     The  term 
substantial   construction  may   itself   be   subdivided   to  embrace     durability, 
strength  of  frame  and  great  weight-carrying  floors  which  are   free  from 
vibration.      In    factories    of   a   certain    class    even    sanitary   conditions    are 
achieved  at  greatly  reduced  cost  over  other  materials.     Indeed,  concrete  has 
entered  into  every  feature  of  modern  factory  or  mill  construction,  from  foun- 


REIXFORCED  COXCRETE 

dation  to  roof,  and  the  tendency  to-day  is  more  and  more  in  the  direction 
of  concrete  construction  throughout.  And  while  the  factory,  owing  to  con- 
crete, has  improved  as  a  building  type,  there  has  been  a  corresponding 
improvement  in  the  processes  of  its  construction,  the  introduction  of  econ- 
omies which  make  for  greatly  reduced  cost. 

In  succeeding  pages  are  shown  factory  buildings  of  various  designs, 
but  all  possessing  features  which  indicate  the  growing  popularity  of  con- 
crete as  a  structural  material.  It  is  not  the  purpose  here  to  go  into  minute 
detail  of  mill  construction,  but  rather  to  show  that  the  concrete  factory  is 
a  reality  and  admirably  adapted  to  the  purposes  intended. 

Concrete   Factories  in   Philadelphia 

Among  the  great  manufacturing  centers  of  the  United  States  is  the 
city  of  Philadelphia,  and  it  is  only  natural  that  in  that  metropolis,  which  is 
in  close  touch  with  the  greatest  cement  producing  district  of  the  country, 
should  be  found  many  examples  of  the  new  type  of  factory.  It  was  some 
four  or  five  years  ago  that  an  enterprising  firm  of  architects  and  engineers 
in  that  city,  Messrs.  Ballinger  &  Perrot,  discerning  the  future  of  concrete, 
began  to  give  serious  consideration  to  concrete  construction  as  applied  to 
industrial  plants.  In  the  brief  period  designated,  they  have  designed  and 
constructed  a  large  number  of  plants  in  Philadelphia  and  neighboring 
cities. 


A    GOOD   EXAMPLE    Of-     INTERIOR    CONSTRUCTION    OF    CONCRETEj       PLAN'I     OF    THE    BILGRAM 

>  MACHINE    SHOP,    PHILADELPHIA 

[72] 


CONCRETE  IN  FACTORY  CONSTRUCTION 


CONCRETE    BUILDING    OF    THE    CRANE     ICE     CREAM     COMPANY,    PHILADELPHIA 

Concrete  in  Machine  Shop  Construction 

One  of  the  first,  if  net  the  first,  manufacturing  plants  in  Philadelphia 
in  which  concrete  was  introduced,  is  the  machine  shop  of  Hugo  Bilgram, 
designed  and  constructed  by  Ballinger  &  Perrot.  We  show  an  exterior  and 
interior  view  of  the  shop.  All  the  floors  and  the  roof  are  built  of  reinforced 
concrete.  The  wearing  surface  of  the  floors  is  of  maple  nailed  to  wooden 
sleepers,  with  cinder  concrete  between  the  latter.  The  building  is  120 
feet  long  and  100  feet  deep.  For  a  little  more  than  half  the  depth  it  is  two 
stories  high  with  provision  for  three  additional  stories.  The  interior  view 
shows  the  substantial  character  of  the  concrete  work.  The  building  also 
contains  the  first  saw-tooth  skylights  erected  in  Philadelphia  which  are 
made  of  concrete  and  glass. 

Crane  Company  Ice  Cream  Factory  Built  of  Concrete 

Reference  has  been  made  to  the  value  of  concrete  where  sanitary  pre- 
cautions are  essential.  In  this  connection  the  factory  of  the  Crane  Ice 
Cream  Company,  Philadelphia,  is  an  interesting  example.  The  name  of 
this  company  is  almost  a  household  word  in  Philadelphia  and  vicinity,  the 
extensive  business  it  conducts  having  been  founded  upon  the  excellence  and 
purity  of  its  products.  Therefore,  cleanliness  and  proper  sanitary  precau- 
tions were  important  considerations  when  a  new  and  larger  factory  became 
a  necessity.  That  concrete  has  answered  every  purpose  in  this  instance, 

[73] 


REIXFORCED  COXCRETE 

the  President  of  the  Company,  Mr.  Robeit  Crane,  will  attest.  The  two 
views  of  the  factory  shown  herewith  indicate  its  substantial  character.  The 
interior  view  discloses  the  immense  concrete  girders,  with  a  span  of  forty 
feet,  designed  to  carry  a  load  of  150  Ibs.  to  the  square  foot.  Another  rea- 
son fcr  the  adoption  of  concrete  was  the  fact  that  a  material  capable  of 
resisting  the  action  of  salt  water  \vas  necessary.  Mersrs.  Ballin0er  &  Per- 
rot  conducted  experiments  along  this  line  by  immersing  a  concrete  cube 
containing  steel  rods  in  brine,  where  it  was  allowed  to  remain  for  seven 
months.  When  the  cubes  were  finally  broken,  the  rods  were  found  to  be  in 
perfect  condition.  The  building,  which  covers  an  area  of  no  by  240  feet, 
is  also  roofed  with  concrete.  While  the  outer  walls  are  brick  the  entire 
interior  construction  is  concrete.  The  various  departments  comprise  the 
store,  offices,  sleeping  and  living  rooms,  dining  room  and  kitchen  for  em- 
ployes, ice  cream  and  pastry  departments,  shipping  and  storing  depart- 
ments, and  the  power  plant,  the  latter  including  boilers,  engines,  dynamos 
and  ice  making  machinery.  At  the  rear  of  the  lot,  and  entirely  cut  off 
from  the  factory,  are  concrete  stables  with  the  stalls  on  the  second  floor. 

Concrete  Plant  of  the  Victor  Talking  Machine  Company 

A  third  structure  is  the  plant  of  the  Victor  Talking  Machine  Co.,  in 

Camden,  N.  J.     The  original  plant  was  of  the  slow  burning  mill  type,  the 

various   buildings    forming   a   hollow    square.      The   exterior   view    shown 

herewith  is  that  of  a  new  concrete  building  containing  the  executive  of- 


CONCRETE    GIRDERS    AND    COLUMNS    IN    THE    FACTORY    OF    THE     CRAME     ICE     CRE'XM     COM- 
PANY,   PHILADELPHIA 


[74] 


COXCRETE  IX  FACTORY  CONSTRUCTION 


DETAIL   OF  CONSTRUCTION   OF  THE   CONCRETE    PLANT    OF    THE    JEANESVILLE    IRON    WORKS 

COMPANY 

fices  and  pressing  plant.  It  is  the  latest  addition  to  the  factory.  It  has  a 
frontage  of  i/o  feet  on  one  thoroughfare  and  70  feet  on  another.  It 
comprises  four  stories  of  reinforced  concrete  with  brick  walls.  The  inte- 
rior view  shows  the  reinforced  concrete  columns  and  girder  construction. 
In  the  power  house  the  engines,  dynamos,  etc.,  rest  on  a  reinforced  concrete 
iioor  over  the  boiler  room.  Xo  perceptible  vibration  occurs  in  the  floors 
when  the  machinery  is  running.  The  view  of  the  engine  room  shows  rein- 
forced concrete  girders  with  a  span  of  40  feet.  During  a  vibration  test 
a  coin  placed  on  edge  on  one  of  the  engines  remained  in  that  position 
while  the  machinery  was  in  operation.  In  adopting  concrete  construction 
the  company  was  influenced  by  the  fact  that  it  had  sustained  a  serious  loss 
by  tire,  involving  not  only  the  destruction  of  valuable  property  but  a  serious 
delay  in  manufacturing.  The  insurance  was  materially  reduced  on  the 
new  building. 

The  yeanesville  Iron  Works  Plant 

The  next  example  of  mill  construction  shows  concrete  walls  finished 
and  in  course  of  construction.  The-  pictures  are  exterior  views  of  the 
Jeanesville  Iron  Works,  at  Hazleton,  Pa.,  one  a  general  view  of  the  works 
and  the  other  illustrating  the  preliminary  bu:l:ling  operati?ns  involving 
the  use  of  forms.  A  very  impoitai  t  circumstance  in  connection  with  the 
building  of  this  mill  was  the  fact  that  the  walls  of  concrete  cost  less  than 
brick.  There  was  a  great  deal  of  mountain  stone  or  boulders  to  be  re- 

[75] 


REINFORCED  CONCRETE 


AN    EXAMPLE    OF  CONCRETE    FACTORY    WITH     BRICK    AND    STONE    VENEER;      PLANT     OF    THE 
VICTOR    TALKING   MACHINE    COMPANY    AT   CAMDEN     NEW    JERSEY 


ENGINES    IN    THE    CAMDEN    PLANT    OF    THE    VICTOR    TALKING    MACHINE    COMPAN  f,    RESTING 
ON    CONCRETE    GIRDERS    WITH    A    SPAN    OF   40  FEET 


176] 


CONCRETE   IN   FACTORY   CONSTRUCTION 


THE    UALTIMORE    PRINTING     PLANT    OF     THE    FRIEDENWALD     COMPANY,    BUILT     OF     REIN- 
FORCED   CONCRETE 

moved  and  these  were  utilized  in  the  form  of  crushed  stone  for  the  con- 
crete, thereby  cheapening  materially  the  cost  of  preparing  the  site.  The 
expense  for  this  would  have  been  considerable  with  any  other  type  of 
wall,  saving,  as  it  did,  the  cost  of  transporting  bricks,  etc.  In  excavating 
the  rock  it  also  proved  convenient  to  establish  a  large  reservoir  for  pro- 
tection in  event  of  fire.  Altogether  the  mill  is  an  excellent  example  of  the 


METHOD    OF    CONSTRUCTING    THE    CONCRETE    WALLS    OF     THE     PLANT     OF     THE     FRIEDEN- 
WALD   COMPANY,    BALTIMORE 


(771 


REIXFORCED  CONCRETE 

economy  of  concrete  construction  in  an    environment    such     as     has     been 
described. 

A  Printing  Plant  in  Baltimore  of  Reinforced  Concrete 

A  three-story  and  basement  building  of  fireproof  construction  through- 
out, with  walls,  columns,  floors  and  roof  all  of  reinforced  concrete,  is  the 
Friedenwald  Printing  House,  in  Baltimore.  The  building  fronts  on  three 
streets,  the  greatest  length  being  280  feet  with  a  depth  of  about  80  feet.  A 
concrete  stack  100  feet  high  and  54  inches  in  diameter  is  a  special  feature 
of  the  plant.  The  structure  has  attracted  a  great  deal  of  attention  and  is 
regarded  as  one  of  the  show  buildings  of  the  town,  public  interest 
being  heightened  by  the  fact  that  it"  is  concrete.  An  exterior  view  of  the 
plant  from  the  drawing  of  Ballinger  &  Perrot  is  shown.  A  second  view 
shows  the  forms  in  place  during  wall  construction.  In  this  building  all  the 
moldings  and  ornamental  features  are  cast  in  concrete.  The  exterior  sur- 
face will  be  dressed  with  a  pneumatic  tool.  The  base  of  the  building  and 
certain  other  features  will  be  more  roughly  dressed  than  the  piers  in  order 
to  establish  a  contrast  in  texture  and  finish.  In  brief,  the  architects  are 
seeking  to  procure  a  characteristic  expression  in  concrete  without  regard  to 
brick  and  stone  designs.  Concerning  the  practical  features  of  the  building 
the  heavy  presses  will  be  carried  on  concrete  floors.  An  innovation  will  be 
the  wide  \vindow  openings,  affording  lots  of  light,  which  is  easily  accom- 
plished in  concrete  construction,  and  which  has  been  adopted  by  the  above 
firm  as  a  permanent  feature  of  their  factory  plans.  The  unit  system 
adapted  to  the  Kahn  bar  was  employed  in  the  construction  of  this  building. 

A  Substantial  Concrete  Structure  in  Philadelphia 

The  early  stages  of  work  in  the  construction  of  an  addition  to  the  glue 
factory  of  F.  W.  Tunnell  &  Company,  Philadelphia,  are  shown  in  the 
accompanying  photograph.  The  building,  which  is  43  by  104  feet  and  three 
stories,  is  intended  for  drying  purposes.  The  walls,  columns,  floors  and 
roof  are  reinforced  concrete.  The  need  for  unobstructed  space  on  the  two 
upper  floors  was  easily  met  with  concrete  by  the  introduction  of  concrete 
girders  with  a  span  of  39  feet,  thus  doing  away  with  columns.  Reinforced 
concrete  cantilevers  projecting  five  feet  and  carrying  the  floors  and  roof  of 
an  adjoining  building  constitute  an  interesting  feature  of  this  structure. 

d  Model  Concrete  Printing  Plant 

The  highest  completed  concrete  building  in  Philadelphia  up  to  date 
was  designed  by  the  above  firm  for  the  Ketterlinus  Lithographic  Manufac- 
turing Company.  As  shown  in  the  accompanying  photograph,  it  is  a  sub- 
stantial structure  and  an  addition  to  an  older  building.  It  is  reinforced 
concrete  with  wall  piers  veneered  with  brick  to  correspond  with  other 
parts  of  the  plant.  It  is  eight  stories  with  basement.  The  reinforced  con- 
crete floors  are  designed  to  carry  a  load  of  400  pounds  to  the  square  foot. 

[78] 


CONCRETE  IN  FACTORY  CONSTRUCTION 


[791 


REINFORCED  CONCRETE 


Heavy  presses  weighing  from  15  to  20  tons  are  installed  in  the  third, 
fourth  and  fifth  stories.  The  absence  of  the  excessive  vibration  which 
took  place  in  the  old  building  when  the  presses  were  running  is  a  conspicu- 
ous advantage  in  the  new  building,  and  a  striking  example  of  the  virtue  of 

concrete  in  this  respect.  As  a 
matter  of  fact  the  rigidity  of 
the  new  building  when  par- 
tially completed  served  to 
decrease  vibration  in  the  ad- 
joining structure.  Reinforced 
concrete  columns  are  used  ex- 
clusively in  the  four  upper 
stories  and  on  the  lower  floors 
with  the  addition  of  a  steel 
core  to  avoid  increasing  their 
size.  It  is  said  this  plant  en- 
joys the  distinction  of  being 
the  only  building  in  the  con- 
gested portion  of  the  city  in- 
sured by  the  Associated  Fac- 
tory Mutual  Insurance  Com- 
panies, which  is  due  to  its  su- 
perior construction  and  equip- 
ment. The  windows  have 
metal  frames  and  wire  glass, 

A  Pittsburg  Concrete 
Warehouse   and  Factory 

A  tall  structure,  contain- 
ing offices,  warehouse  and  fac- 
tory is  that  erected  for  the 
Bernard  Gloekler  Company  of 
Pittsburg,  manufacturers  of 
refrigerators  and  store  fix- 
tures. It  is  ten  stories  and 
basement,  80x100  feet,  and  of 
reinforced  concrete  through- 
out, including  the  walls  and 
ornamental  features,  except- 
ing the  main  entrance  and 
dentil  course  of  the  cornice 
which  are  artificial  stone.  It 

CONCRETE     CHIMNEY     AT     THE     C.    J.     MATTHEWS  .  . 

LEATHER  MANUFACTURING  PLANT  is  one  of  the  notable  examples 


[80] 


CONCRETE  IN  FACTORY  CONSTRUCTION 


A  NOTABLE  EXAMPLE  OF  CONCRETE  CONSTRUCTION   WORK;  A   TEN-STORY  BUILDING   OF  THE 
BERNARD  GLOELKLER  COMPANY,  PIT1SBURG 


[81] 


REINFORCED  CONCRETE 


DETAIL    OF   CONCRETE    FLOOR,  BEAM,    GIRDER,    AND    COLUMN 
CONSTRUCTION,   IN    FACTORY   OF  MERRITT    &   COMPANY 

of  concrete  construction.  A  tower  containing  three  tanks,  two 
of  5,000  gallon  capacity,  and  one  of  20,000  gallon  capacity,  and  a 
reinforced  concrete  chimney  48  inches  in  diameter  and  165  feet  high,  are 
special  features.  The  whole  constitutes  a  fireproof  structure  of  the  most 
substantial  character  and  its  height  indicates  that  concrete  is  perfectly 
adapted  to  structures  of  the  skyscraper  type. 

A  Concrete  Factory  Chimney  and  Floors 

Concerning  factory  details  it  will  be  interesting  to  make  special  men- 
tion of  the  tall  chimney  and  floors  of  reinforced  concrete  shown  in  the  ac- 
companying pictures  of  the  C.  J.  Matthews  Leather  Manufacturing  plant, 
Philadelphia.  The  chimney  supplanted  a  steel  chimney,  which  was  not  sat- 
isfactory. The  concrete  chimney  has  been  subjected  to  gases  and  heat  for 
the  period  of  several  months  without  perceptible  influence.  In  extensions 
made  to  the  plant  concrete  floors  were  introduced.  These  floors  exemplify 
in  the  highest  degree  the  value  of  concrete  in  affording  resistance  to  vibra- 
tion. The  glazing  machines  were  placed  on  the  third  floor  and  are  operated 
with  practically  no  vibration,  which  was  so  extreme  on  wooden  floors  that 
[82] 


CONCRETE  IN  FACTORY  CONSTRUCTION 

it  was  necessary  tc  remove  the  machines.  The  vibration  of  these  machines 
is  such  that  in  another  plant  in  the  same  city  they  were  placed  on  the 
ground  floor  and  anchored  to  stone  foundations.  In  the  Matthews  plant 
another  interesting  feature  of  the  concrete  work  consists  of  reinforced  con- 
crete cantilevers,  projecting  18  inches,  which  carry  a  dividing  wall  load  of 
80  tons  on  each  cantilever. 

All  of  the  factories  and  buildings  described  above  were  designed  and 
constructed  by  Ballinger  &  Perrot.  The  experience  of  this  firm  has  led 
them  to  the  conviction  that  concrete,  more  than  any  other  material,  ap- 
proaches the  ideal  in  the  construction  of  industrial  plants. 

A  Huge  Factory  of  Concrete  Blocks  in  Trenton 

Notwithstanding  the  fact  that  the  buildings  are  but  partly  erected,  the 
huge  plant  of  the  Union  Paper  Cup  Co.,  at  Trenton,  N'.  J.,  is  worthy  of 
special  notice  in  these  pages.  This  company,  of  which  Mr.  Henry  R.  Heyl, 
of  Philadelphia,  is  president,  will  engage  in  the  manufacture  of  paper 
cups  and  bottles  on  a  large  scale,  a  patent  product  which  promises  to  tax 
even  the  resources  of  the  enormous  plant.  There  will  be  many  buildings 
erected  but  it  is  only  necessary  to  state  that  the  main  structure  is  600  by 
50  feet,  a  second  building  220  by  50  feet,  and  a  third,  50  by  50  feet,  to  give 
some  idea  of  the  capacity  of  the  plant,  which  is  intended  to  turn  out  400,000 
paper  milk  bottles  per  day.  The  entire  plant  will  be  of  concrete  block  con- 
struction except  the  floor  in  the  main  building,  which  will  be  of  wood. 
In  other  respects  the  buildings  are  concrete  from  foundation  to  roof,  and 
will  be  one  story  high.  Mr.  Heyl,  who  has  direct  supervision  of  the  build- 
ing operations,  has  found  upon  experiment  that  it  has  been  possible  to  ef- 
fect a  saving  of  50  per  cent,  over  brick  construction  by  the  use  of  concrete 
blocks  for  walls.  The  blocks  have  also  been  used  for  column  construction, 
rods  being  inserted  in  the  blocks  and  the  whole  grouted  with  cement. 
Girders  and  roofs  are  of  reinforced  concrete.  The  spans  in  some  instances 
are  50  feet  clear.  It  was  chiefly  the  fireproof  properties  of  concrete  which 
led  to  its  adoption  in  this  factory,  but  the  astonishingly  low  cost  of  wall  con- 
struction by  the  hollow  block  system  is  another  advantage  thoroughly 
appreciated  by  the  company.  The  blocks  are  made  at  the  factory  site. 
Two  views  of  the  factory  are  presented,  one  a  perspective  view  of  early 
work  in  the  big  main  building,  which  clearly  indicates  its  vast  size.  A 
second  view,  taken  about  the  middle  of  September,  shows  the  work  com- 
pleted up  to  that  period.  This  plant  promises  to  be  a  record  breaker  in  the 
matter  of  substantial  and  cheap  construction. 

A  Reinforced  Concrete  Factory  in  Camden 

An  excellent  example  of  concrete  cage  construction  is  shown  in  the 
accompanying  picture  of  the  Expanded  Metal  Locker  Company's  factory 
at  Camden,  N.  J.,  built  and  operated  by  Merritt  &  Co.,  of  Philadelphia, 

[83] 


REINFORCED  CONCRETE 

engineers  and  builders  of  expanded  metal  fireproof  structures.  As  the 
company  announced  when  it  erected  this  building:  "A  doctor  who  takes 
his  own  medicine  usually  inspires  confidence/7  and  that  the  company  has 
done  in  this  instance.  The  structure  is  a  five-story  reinforced  concrete 
building,  74  feet  by  80  feet,  for  their  own  use. 

Early  last  summer  fire  destroyed  a  four-story  building  which  formed 
a  portion  of  their  locker  manufacturing  plant  at  Camden,  N.  J.  The  build- 
ing was  used  for  painting,  shipping  and  storage,  the  main  factory  being 
uninjured.  The  new  building  is  of  "cage"  construction,  the  entire  load, 
including  both  exterior  and  partition  walls,  being  carried  on  columns. 
The  latter  and  the  girders  are  of  concrete  reinforced  with  steel  rods.  The 
floors  and  roofs  are  of  concrete  and  expanded  metal. 

A  comparison  of  the  old  and  new  rates  of  insurance  will  be  of  inter- 
est. The  old  structure  was  a  fairly  good  example  of  brick  wall  and 
wood  joist  construction,  but  the  insurance  rate  was  $1.63  on  the  build- 
ing and  $1.94  on  the  contents.  On  the  new  structure  the  rate  is  82  cents 
on  the  building  and  $i  on  the  contents. 

There  is  shown  in  addition  to  the  exterior  view  of  the  factory  an  ex- 
cellent picture  of  concrete  floors,  beams,  girders  and  columns.  The  sub- 
stantial character  of  the  work  is  very  apparent. 


THESE    GLAZING    MACHINES,    WHICH    CAUSE    EXTREME   VIBRATION,  ARE    SUPPORTED  ON  THE 
CONCRETE    FLOORS    OF    THE    C.   J.   MATTHEWS    LEATHER    MANUFACTURING 

PLANT,     PHILADELPHIA 
[84] 


CONCRETE  IN  FACTORY  CONSTRUCTION 


INTERIOR    VIEW    OF  A    CONCRETE    STAIRWAY,  SHOWING  THE 
USE    OF    AN    EXPANDED    METAL    REINFORCEMENT 

A  Cement  Storage  House  Built  of  Concrete 

A  building  of  concrete  for  the  storage  of  cement  at  the  Martin's 
Creek  plant  of  the  Alpha  Portland  Cement  Company,  in  the  Lehigh 
cement  district,  is  another  exemplification  of  the  physician  taking  his  own 
prescription.  This  structure,  also  the  work  of  Merritt  &  Co.,  is  concrete 
throughout.  The  accompanying  photograph  gives  the  reader  a  very  clear 
conception  of  the  building. 

The  building  is  387  ft.  long  by  98  ft.  wide  and  33  ft.  high  from  the 
floor  to  the  eaves.  The  building  has  no  windows,  but  is  lighted  from  the 
roof.  Cement  is  carried  to  it  by  belt  conveyers,  and  it  is  so  designed 
that  the  whole  or  any  portion  of  the  building  may  be  rilled  to  the  roof 
with  cement  in  bulk  without  danger  of  the  walls  bulging  outward.  The 
walls  are  12  inches  in  thickness  and  are  reinforced  by  6-inch  mesh,  No. 
4  gauge,  expanded  metal  and  by  steel  rods.  At  intervals  of  10  feet  there 
are  reinforced  concrete  buttresses  on  the  outside  of  the  building. 

In  view  of  the  fact  that  there  would  be  absolutely  no  combustible 
material  used  in  the  building,  the  owners  intended  at  first  to  use  sheathing 
carried  upon  the  steel  trusses.  The  upper  surface  was  to  have  been  of 
ordinary  felt  and  slag  construction.  A  few  days  before  the  signing  of  the 
contract  a  similar  roof  on  one  side  of  the  Alpha  stock  houses  took  fire  and 

[85] 


REINFORCED  CONCRETE 


[35] 


CONCRETE  IN  FACTORY  CONSTRUCTION 

was  in  a  large  measure  destroyed,  causing  considerable  loss  through  the 
damage  by  water  to  the  cement  stored  in  the  building.  The  owners  there- 
upon decided  that  no  wood  should  be  used  in  any  portion  of  the  build- 
ing and  the  specifications  were  changed,  so  that  the  new  building  has  a 
roof  of  cinder  concrete  reinforced  with  expanded  metal,  having  the  ordin- 
ary slag  finish  on  top.  This  provides  a  building  about  which  there  is  ab- 
solutely nothing  to  burn. 

Roof  and  Stairway  of  Concrete  and  Expanded  Metal 

The  adaptability  of  concrete  and  expanded  metal  in  factory  construc- 
tion has  been  developed  to  a  remarkable  degree  in  recent  years.  The 
combination  of  the  two  materials  has  proven  especially  valuable  as  a  fire 
resistant.  An  interesting  example  of  concrete  and  expanded  metal  roof 
construction  is  shown  and  also  an  illustration  of  the  use  of  concrete  and 
expanded  metal  in  the  construction  of  a  stairway,  both  the  work  of  Mer- 
ritt  &  Company. 

A  Concrete  Abattoir 

Probably  few  happenings  in  recent  years  have  so  aroused  the  Ameri- 
can public  and  created  such  wide-spread  interest  in  this  country  and 
abroad  as  recent  allegations  embodied  in  the  report  of  government 
inspectors  concerning  sanitary  conditions  at  the  great  Chicago  packing 
houses.  In  view  of  what  has  transpired,  the  concrete  structure  about  to 
be  described  possesses  more  than  ordinary  interest.  It  is  the  packing 
plant  of  the  Arbogast  &  Bastian  Co.,  at  Allentown,  Pa.  The  plant  was 
designed  by  Mr.  Percy  A.  Kley,  a  prominent  Philadelphia  engineer  and 
architect.  It  is  said  to  be  the  first  concrete  packing  plant  erected  in  the 
United  States,  and  comprises  a  number  of  buildings.  The,  accompany- 
ing photographs  show  the  exterior  of  building  A,  in  which  the  sausage 
manufacturing  department  is  located,  and  an  interior  view  of  concrete 
construction  in  which  round  and  square  columns,  beams  and  girders  are 
shown. 

The  plant  consists  of  six  buildings  from  four  to  five  stories  high  and 
of  varying  dimensions.  The  largest  is  approximately  40  by  82  feet.  The 
foundations  are  concrete  and  the  walls  brick.  The  interior  construction 
throughout  is  concrete,  even  to  the  lintels  of  doors  and  windows.  The 
columns,  floors,  girders,  beams  and  roof  are  of  concrete.  The  girder  spans 
in  some  instances  are  about  16  feet  and  beam  spans  17  feet.  In  one  build- 
ing the  cellar  is  utilized  as  the  hide  department.  The  general  offices  and 
beef  killing  department  are  on  the  first  floor.  Above  these  are  the  cold 
storage  and  machinery  departments,  and  on  the  third  floor  the  hog  killing 
is  conducted.  The  fourth  floor  is  the  fertilizer  department.  All  the  build- 
ings are  on  the  same  general  plan  so  far  as  concrete  construction  is  con- 
cerned. 

[87] 


REINFORCED  CONCRETE 


[88] 


CONCRETE  IN  FACTORY  CONSTRUCTION 


"\ 


THE    EXPANDED    METAL   LOCKS   FACTORY   OF   MERRITT   &   COMPANY,   TRENTON,   NEW   JERSEY; 
BUILT   OF    REINFORCED    CONCRETE 


A    CONCRETE    STOREHOUSE;    THE    PLANT  OF  THE    ALPHA    PORTLAND    CEMENT    COMPANY    AT 

MARTINS    CREEK 


[89] 


REINFORCED  CONCRETE 


:u 


CONCRETE  IN  FACTORY  CONSTRUCTION 


BUILDING    A,    CONCRETE    ABATTOIR    OF    ARBOGAST    &    BASTIAN    COMPANY    ALLENTOWN,  PA.j 
A    MODEL    OF    THIS    TYPE    OF    CONSTRUCTION 


INTERIOR     VIEW     OF    THE     ABOVE     ABATTOIR,    SHOWING     THE     CONCRETE     CONSTRUCTION. 
NOTE    THE    ROUND    AND    SQUARE    CONCRETE    COLUMNS 

[91] 


REINFORCED  CONCRETE 


THE   REINFORCED   CONCRETE   MILL  AT   PASSUMPSIC,  VERMONT;   BUILT   WITHOUT   THE   AID 
OF  A  CONTRACTOR    BY   THE   PRESIDENT  AND   TREASURER   OF   THE  COMPANY 

As  stated,  this  is  the  first  modern  concrete  abattoir  in  this  country. 
In  undertaking  its  construction  Mr.  Kley  so  designed  the  plant  that  it 
should  accord  in  every  respect  with  the  conditions  prescribed  by  the  De- 
partment of  Agriculture.  Special  attention  was  given  to  the  problem  of 
securing  many  departments  in  one  plant  which  should  at  the  same  time  be 
-entirely  independent  of  each  other  where  necessary  to  insure  absolutely 
safe  sanitary  conditions.  It  was  found  that  concrete  was  admirably  adapt- 
ed for  this  purpose.  Not  only  did  it  lend  itself  to  construction  of  a  durable, 
fireproof  and  sanitary  character,  but  was  especially  valuable  in  the  install- 
ment of  a  perfect  cold  storage  system.  The  Allentown  abattoir  is  a  valu- 
able example  of  the  utility  of  concrete  for  the  purposes  described. 

A  Factory  Built  Without  a  Contractor 

An  interesting  example  of  concrete  mill  construction  is  the  plant  of  the 
Passumpsic  Fiber  Leather  Co.,  at  Passumpsic,  Vt.  Not  only  is  the 
mill  somewhat  out  of  the  ordinary,  but  was  built  without  aid  of  a  con- 
tractor by  Mr.  Stephen  Chase  and  his  brother,  Mr.  Theodore  W.  Chase,  who 
are  President  and  Treasurer  respectively  of  the  company.  Mr.  I.  W.  Jones, 
of  Milton,  N.  H.,  was  the  engineer  and  architect. 

All  the  stone  used  in  the  concrete  work  was  broken  by  the  company's 
•crusher.  The  plant  consists  of  the  main  mill,  a  two-story  structure,  about 
60  by  60  feet,  with  a  reinforced  concrete  flume;  a  dry  house,  office,  boiler 
house  and  store  house.  The  main  building,  which  is  perhaps  the  most  inter- 
esting, has  two  concrete  floors.  The  lower  floor  is  on  a  rock  fill  and  the 
upper  is  4  I -2-inch  concrete  reinforced  with  3-inch  expanded  metal.  This 
floor  is  supported  by  concrete  columns  18  by  18  inches.  The  main  girders 
are  1 8  by  32  inches,  and  the  joists,  which  are  spaced  4  feet  10  inches  apart,  are 
12  by  1 8  inches,  with  a  span  of  about  14  feet.  The  girders  and  joists  are 
heavily  reinforced  with  corrugated  rods  and  stirrups.  The  floor  is  planned 
'  [92] 


CONCRETE  IN  FACTORY  CONSTRUCTION 

for  a  load  of  300  pounds  and  to  hold  eight  large  heating  engines.  The  walls 
below  are  of  reinforced  concrete  with  pilasters  above  and  windows  be- 
tween. The  walls  of  the  upper  floor  are  of  reinforced  pilasters  and  cap- 
girder,  with  brick  panels  and  windows.  Above  the  cap-girders  are  brick 
parapets,  the  roof  being  supported  by  steel  trusses. 

The  flume,  an  end  of  which  is  a  part  of  one  wall  of  the  building,  is  20 
feet  wide  inside,  and  about  50  feet  long.  The  sides  are  heavily  buttressed 
with  a  6-inch  panel  between.  The  flume  is  14  and  18  feet  deep,  with  1 8-inch 
girders  over  the  first  part  and  22— inch  girders  over  the  second  part.  The 
latter  portion  is  covered  with  a  4-inch  floor.  The  end  of  the  flume  is  18 
inches  thick,  reinforced  with  7-8-inch  round  rods  over  3  inches  apart.  The 
end  is  supported  by  a  iQ-foot  arch,  2  feet  6  inches  thick  at  the  crown,  in 
which  are  two  holes  for  draught  tubes,  and  over  which  the  wheels  are  placed. 

Over  thirty  tens  of  steel  rods  were  used  in  the  building  and  flume. 

The  First  Concrete  Plant  in  New  York  City 

The  fact  that  concrete  will  be  one  of  the  important  structural  materials- 
in  New  York  City  during  the  next  few  years  is  indicated  by  a  contract 
which  has  recently  been  given  for  the  only  reinforced  concrete  office  build- 
ing in  New  York.  This  is  the  first  time  in  the  history  of  the  city  that 
permission  has  been  secured  from  the  Building  Department  for  the  erection 
of  an  industrial  structure  of  this  type  and  the  plans  which  have  been  made 


METHOD   OF  CONSTRUCTION   OF  THE  MILL.      THE  COLUMNS  ARE   18"  x  18";  THE  MAIN 
GIRDERS   18"  x  ji"  AND   THE  JOISTS  i»"  x  18" 


[931 


REINFORCED  CONCRETE 

are  being  watched  with  interest  by  architects,  engineers  and  builders 
throughout  the  country. 

The  building  will  be  eleven  stories  high  and  will  be  constructed  of 
concrete  throughout.  Unlike  the  majority  of  concrete  industrial  structures 
this  building  will  not  be  faced  with  brick.  The  front  of  the  building  will 
be  finished  in  concrete  only  in  a  more  careful  manner  than  has  been  done 
heretofore  with  the  result  that  the  facade  will  not  suffer  in  comparison  with 
stone  or  brick  fronts.  The  finish  will  be  of  an  honest  expression  of  the 
construction  of  the  building  and  will  not  attempt  in  any  way  to  imitate 
any  other  form  of  constructional  material. 

The  building  will  be  erected  on  the  plot  at  231  to  241  West  39th  Street 
for  the  McGraw  Realty  Company.  The  subsidiary  concern  of  the  McGraw 
Publishing  Company.  The  plans  were  drawn  by  Radc'iffe  &  Kelley,  archi- 
tects, who,  with  Professor  Wm.  H.  Burr,  consulting  engineer,  and  Walter 
S.  Timmis,  mechanical  engineer,  have  charge  of  the  construction  work. 
The  builder  is  Frank  B.  Gilbreth. 

The  McGraw  Building  as  it  will  be  called  has  a  frontage  of  126  feet 
4  inches,  and  a  depth  of  98  feet  9  inches.  The  basement  is  planned  for  a 
press  room.  The  first  floor  will  be  used  for  finishing  and  shipping  the 
McGraw  publications  and  the  second  and  third  floors  will  be  occupied  by 
the  office  force  of  the  McGraw  Publishing  Company.  The  remainder  of 
the  building  will  be  rented  as  offices. 


FACTORY    WALLS     OF     CONCRETE     BLOCKS;    PLANT     OF     THE     UNION     PAPER     COMPANY,  NEAR 

TRENTON,  NEW  JERSEY 

[94] 


CONCRETE   IX   FACTORY   CONSTRUCTION 


THE    FIRST    CONCRETE    OFFICE    BUILDING    IN    NEW    YORK;    AN   ELEVEN-STORY   REIN- 
FORCED   CONCRETE    OFFICE    BUILDING    NOW    BEING    ERECTED    FOR 
THE    McGRAW    REALTY    COMPANY 


Particular  care  has  been  exercised  in  designing  the  columns  with 
beam  and  girder  connections  to  them.  They  will  be  more  simple  in  design 
than  those  commonly  used  and  have  steel  reinforcements  of  no  greater 
weight  than  usual  but  of  an  inherent  stability  which  will  give  a  strength  far 
greater  than  has  hitherto  been  secured  with  the  given  weight  of  steel.  The 
details  of  the  structure  are  also  of  concrete  including  all  partitions,  shaft 
enclosures  and  stairways.  The  doors  are  covered  with  metal,  the  window 
frames  are  of  metal  glr.zccl  with  wire  glass.  The  equipment  of  the  building 

[95] 


REINFORCED  CONCRETE 

generally  will  be  such  as  to  give  the  greatest  fire  protection  and  thus  insure 
the  lowest  insurance  rates. 

The  accompanying  diagram  shows  the  front  elevation  of  the  McGraw 
Building. 

The  illustration  of  the  General  Creosoting  Plant  at  Somerville,  Texas, 
represents  a  model  tie  treating  plant  erected  for  the  Santa  Fe  Railroad. 

The  construction  of  the  buildings  was  somewhat  complicated  from 
the  fact  that  all  the  cylinders  and  boilers  were  placed  and  set,  and  the 
buildings  erected  around  and  above  them.  There  were  times  also  when 
the  machinery  was  in  service,  while  being  tested,  and  afterwards  actually 
treating  ties,  which  evidently  made  it  rather  inconvenient  to  work  to  the 
best  advantage. 


GENERAL    VIEW    OF    THE    CREOSOTING    PLANT    AT    SOMERVILLE,   TEXAS 

The  buildings  were  erected  and  completed  in  three  and  one-half 
months —  about  the  time  required  to  deliver  structural  steel  on  the  ground, 
and  the  cost  of  the  structure  was  about  six  per  cent,  less  than  the  cost 
of  one  similarly  designed  in  structural  steel  with  concrete  roof  and  wall 
slabs. 

The  work  was  under  the  immediate  charge  of  C.  F.  W.  Felt,  Chief 
Engineer,  Gulf,  Colorado  and  Santa  Fe,  the  buildings  being  designed  and 
built  under  his  direction  by  the  Expanded  Metal  and  Corrugated  Bar 
Company,  R.  L.  Murphy,  Contracting  Engineer. 

The  plant  of  the  Dayton  Malleable  Iron  Works,  designed  by  Peters, 
[96] 


CONCRETE  IN  FACTORY  CONSTRUCTION 


6-|  BARS  WRAPPED 
WITH    SOFT    IRON 
WIRE     EVERY   \Z" 

BOILER  HOUSE  SECTION   A-A 

CYLINDER    AND    BOILER    HOUSE,    CREOSOTING    PLANT,    SOMERVILLE,   TEXAS 


CREOSOTING     PLANT    .AT    SOMERVILLE,     SHOWING    THE    BOILER     HOUSE     UNDER    CONSTRUCTION 


[97J 


REIXFORCED  CONCRETE 


REINFORCED    CONCRETE    PLANT    OF    THE    DAYTON    MALLEABLE    IRON    WORKS,    DAYTON,    OHIO 

Burns  &  Pretzinger,  represents  a  building  with'  spans  averaging  fourteen 
feet  in  length,  and  calculated  to  carry  about  150  pounds  to  the  square  foot. 
This  represents  a  very  common  type  of  mill  building,  in  which  the  main 
structural  members  are  of  reinforced  concrete,  while  the  exterior  walls 
are  of  brick  or  of  concrete  block  construction. 

Concrete  Factories  Previously  Described  in  Cement  Age 

Readers  of  the  CEMENT  AGE  will  recall  having  seen  descriptions  from 
time  to  time  of  many  factories,  mills  and  warehouses,  not  included  among 
those  described  in  preceeding  pages. 

For  example,  there  was  the  Boston  Motor  Mart,  an  immense  concrete 
structure  in  which  7,200  barrels  of  cement  were  used  to  create  an  inde- 
structible, fireproof  building.  This  building  was  described  in  the  August 
number,  1906. 

The  plans  of  the  Ontario  Power  Company,  constructed  throughout  of 
manufactured  stone,  was  an  interesting  example  of  the  adaptibility  of 
concrete  to  that  process,  which  is  described  in  CEMENT  AGE  of  May,  1906. 

The  great  Bush  Terminal  factory  has  been  the  subject  of  several  inter- 
esting articles  and  is  a  most  notable  example  of  concrete  work.  A  fine 
illustration  of  the  interior  view  is  shown  in  an  article  entitled,  "Economies. 
[98] 


CONCRETE  IN  FACTORY   CONSTRUCTION 


AN    EXAMPLE    OF  A  REINFORCED  CONCRETE   FACTORY    AT    AUGSBURG,  GERMANY     THE  WALLS, 
FLOORS,    AND    COLUMNS    ARE    ALL    OF    CONCRETE 


AN    EXAMPLE    OF    CONCRETE    FACTORY    CONSTRUCTION    AT    NYCOPING,    SWEDEN,    SHOWING 
THE    METHOD    OF    ROOF    CONSTRUCTION 


[99] 


REINFORCED  CONCRETE 


ONE    OF    THE     LARGEST     PLANTS     BUILT     OF     REINFORCED     CONCRETE     IN     THE     WORLD;  THE 

COMPANY    AT 

in  the  Use  of  Concrete,"  by  E.  P.  Goodrich,  published  in  CEMENT  AGE  of 
May,  1906. 

The  remarkable  rapidity  with  which  concrete  construction  may  be 
accomplished  constituted  the  striking  features  in  an  article  in  the  March 
number,  1906,  on  the  St.  Croix  Paper  Co.  plant,  at  Sprague  Falls,  Maine. 
This  plant  included  a  2OO-foot  concrete  dam  and  three  large  mills. 

The  Fairbanks  Company  concrete  warehouse  at  Baltimore,  with  floors 
designed  to  carry  250  pounds  live  load,  was  not  only  a  good  example  of  that 
type  of  structure,  but  an  interesting  illustration  of  the  application  of  ex- 
panded metal  in  concrete  construction.  This  building  was  described  in  the 
November,  1905,  number,  which  also  contained  an  illustrated  article  on  the 
Quaker  City  Flour  Mills  Company's  concrete  grain  bins. 

Among  the  many  illustrations  of  concrete  factories  was  that  of  the 
Robert  Gair  plant,  in  Brooklyn,  which  constituted  the  frontispiece  of  the 
January,  1906,  number  of  CEMENT  AGE. 

A  modern  power  plant  in  Baltimore,  that  of  the  Baltimore  Electric 
Co.,  was  the  subject  of  a  special  article  in  the  September,  1905,  number. 
This  is  an  absolutely  fireproof  structure  with  floors  and  roof  of  concrete 
reinforced  with  the  Clinton  fabric.  Concrete  conduits  are  also  a  feature 
of  the  plant. 

An  important  detail  in  factory  construction  was  shown  in  an  illustrated 
article  on  the  tall  concrete  chimney  of  the  Tacoma  Smelter  Company,  an 
immense  column  more  than  300  feet  high. 

An  exceptionally  good  illustration  of  factory  construction  is  the  Pugh 
Power   Building,   Cincinnati,    a   ten-story   structure   built   entirely   of   con- 
crete and  described  in  CEMENT  AGE  for  May,  1905. 
[iool 


COXCKETE  IX  FACTORY  CONSTRUCTION 


OFFICE    AND    FACTORY    STRUCTURES    OF    THE    FOSTER-ARMSTRONG    PIANO     MANUFACTURING 
DESPATCH,  NEW    YORK 

The  River-Bed  power  house  and  pulp  mill  at  Berlin,  N.  H.,  construct- 
ed under  great  difficulties,  is  shown  in  numerous  illustrations  and  descrip- 
tive text  in  the  CEMENT  AGE  of  April,  1905.  In  this  plant  the  concrete  is 
subjected  to  strains  exceedingly  severe,  but  without  showing  any  defects. 
Some  of  the  work  was  also  done  in  extremely  cold  weather.  The  whole 
plant  is  of  the  most  substantial  character. 

An  immense  plant  is  that  of  the  Foster-Armstrong  Company,  piano 
manufacturers,  at  Despatch,  N.  Y.,  described  in  CEMENT  AGE  of  De- 
cember, 1904.  Five  buildings  of  similar  design,  each  250  by  60  feet,  was 
constructed  of  reinforced  concrete.  This  is  one  of  the  early  examples  of 
the  concrete  factory  and  one  that  has  proved  fully  the  worth  of  the  ma- 
terial. 

In  addition  to  the  factories  cited  there  have  been  published  innumer- 
able articles  relating  to  details  of  their  construction. 

What  Time  Has  Verified 

In  conclusion,  it  may  not  be  amiss  to  say  that  CEMENT  AGE  derives 
great  satisfaction  from  the  knowledge  that  its  predictions  concerning  the 
value  of  concrete  in  the  construction  of  industrial  plants  have  been  more 
than  verified.  It  was  among  the  first  in  the  effort  to  advance  an  industry 
that  has  become  one  of  the  greatest  this  country  has  ever  known.  It  is  in- 
teresting to  recall  the  period  when  doubt  assailed  many  who  are  now  among 
the  most  ardent  advocates  of  cement  and  concrete  construction.  The  his- 
tory of  the  great  evolution  would  not  be  complete,  however,  without  tribute 
to  the  memory  of  that  eminent  authority  and  leader  in  the  movement 
for  improved  fireproof  mill  construction,  the  late  Edward  Atkinson.  Sta- 

[101] 


REINFORCED  COX  CRETE 

tistician^  insurance  expert,  political  economist  and  advanced  thinker,  his 
'labors,  whether  in  the  nature  of  contributions  to  cement  literature  or  inves- 
tigation and  practical  experiment,  were  invaluable.  It  has  not  oeen  t\vo 
years  since  Mr.  Atkinson,  in  an  excellent  contribution  to  CEMENT  AGE  of 
April,  1905,  called  attention  to  the  fact  that  the  subject  of  cement  con- 
struction had  attracted  little  attention  from  the  owners  and  managers  of 
large  industrial  plants.  In  his  characteristic  way  he  went  on  to  discuss  the 
application  of  concrete  to  the  dwelling,  warehouse  and  factory,  and  in 
conclusion  set  down  the  following  statements  which  were  prophetic,  indeed, 
in  the  light  of  what  has  since  transpired: 

It  now  seems  to  be  proved  that  large  works  may  be  constructed  of  rein- 
forced concrete  within  ten  per  cent,  or  less  of  the  cost  of  slow  burning  con- 
struction. 

That  such  buildings  are  not  subject  to  as  great  vibration  from  high 
speed  machinery,  or  heavy  slow  movements. 

That  dwelling  houses  can  be  constructed  of  concrete  at  less  cost  than  of 
brick. 

That  large  warehouses  may  be  constructed  at  low  cost  combining  the 
maximum  of  safety  with  durability 

Such  are  the  apparent  conclusions  which  the  writer  has  derived  from 
the  reports  of  tests  and  the  statement  of  facts  submitted  by  the  large  con- 
struction companies,  each  on  its  own  behalf. 

Notwithstanding  the  almost  incredible  development  of  detail  in  con- 
crete construction  which  has  taken  place  since  Mr.  Atkinson  penned  the 
above  words,  his  prophecy  covered  the  whole  field  so  far  as  the  fundamen- 
tal principles  of  construction  are  concerned.  And  it  is  with  justifiable 
pride  that  the  CEMENT  AGE  not  only  recalls  its  own  verified  predictions 
as  to  the  future  of  cement  and  concrete  construction,  but  that  its  pages  con- 
stitute a  valued  record  of  the  early  efforts  and  research  of  such  pioneers  as 
Atkinson,  Norton,  Ransome,  Tucker  and  kindred  spirits. 

Progress  has  not  ceased,  and  though  preceding  pages  give  a  compre- 
hensive idea  of  what  has  taken  place  in  recent  years,  the  achievements 
recorded  up  to  this  time  will  doubtless,  a  decade  hence,  seem  small  indeed. 


[102] 


A    SURFACE    FINISH    FOR 
CONCRETE 

How  a  pleasing  texture  is  obtained  hy  a  simple  and 

inexpensive  process.      Conforms  to  the  plastic 

character  of  the  material 

By 
Henry  H.  Quimby*,  M.  Am.  Soc.  C.  E. 

[In  considering  concrete  as  a  substitute  for  brick  and  stone,  perhaps 
the  most  serious  problem  confronting  the  architect  is  to  obtain 
a  satisfactory  surface  or  finish.  Judging  from  what  the  architect  has  had 
to  say,  his  inability  to  do  this  zvould  seem  to  constitute  his  chief  objection 
to  concrete.  Therefore,  the  first  matter  to  be  determined  is  whether  any  of 
the  countless  workers  in  concrete  have  succeeded  in  obtaining  a  surface 
which  will  conform  to  the  architect's  conception  of  ivhat  is  pleasing  and 
artistic.  Would  a  surface  resembling  dressed  stone  or  granite  (not  the 
familiar  "rock-hewn"  surface  seen  in  concrete  blocks)  be  acceptable?  And 
if  so,  would  the  architect  be  willing  to  use  concrete  if  a  surface  of  that 
character  could  be  obtained,  not  only  by  a  simple  and  inexpensive  process, 
but  one  perfectly  adapted  to  concrete  as  a  plastic  material,  thus  conforming 
to  its  character  without  seeking  to  imitate  other  materials?  It  is  zvith  the 
hope  of  convincing  the  architect  that  this  is  not  only  practical  but  has  al- 
ready been  accomplished,  that  these  pages  are  devoted  to  the  subject  of 
surface  finish  in  concrete.  That  the  problem  is  one  of  wide-spread  interest 
is  shown  by  the  fact  that  it  continues  to  be  the  subject  of  discussion  ivhen- 
ever  and  wherever  concrete  construction  may  be  under  consideration.  The 
proceedings  of  architectural  and  engineering  societies  and  the  pages  of 
technical  journals  continue  to  treat  it  as  an  important  but  unsolved  problem. 

Some  months  ago  CEMENT  AGE,  in  an  article  treating  of  concrete  work 
in  municipal  improvements  in  the  city  of  Philadelphia,  described  an  artistic 
concrete  surface  obtained  by  a  process  devised  by  Mr.  Henry  H.  Quimby, 
Assistant  Engineer,  Bureau  of  Surveys,  in  charge  of  the  design  and 
construction  of  bridges.  The  description  of  Mr.  Quimby's  method  of  treat- 
ing the  surface  of  concrete  in  bridge  construction  was  embodied  in  a  brief 
paragraph  at  the  close  of  the  article,  which  related  to  general  municipal 
work,  and  doubtless  escaped  the  notice  of  many  who  are  especially  inter- 
ested in  the  matter.  In  making  it  the  subject  of  a  special  article  a  number 
of  photographs  are  published  showing  the  variety  in  texture  possible  to 

*Engineer  of  Bridges,  Bureau  of  Surveys,  City  of  Philadelphia. 

[103] 


REINFORCED  CONCRETE 

obtain  ^vith  different  aggregates,  and  also  the  appearance  of  finished  ivork. 
Quite  a  number  of  experiments  have  been  conducted  by  the  Bureau  of  Sur- 
veys with  very  satisfactory  results.  The  bridges  already  constructed  and 
treated  by  this  process  are  well  worth  the  inspection  of  the  architect  who 
still  believes  it  impossible  to  so  treat  a  concrete  surface  that  it  will  not  ap- 
pear monotonous  and  uninteresting.  By  the  simple  process  hereinafter 
described  it  may  be  given  life  and  texture,  and  with  practically  no  likeli- 
hood of  staining  or  '"streaking,"  so  frequently  the  subject  of  complaint  by 
the  architect.  The  exercise  of  due  care  and  insistence  upon  good  work- 
manship will  produce  the  excellent  results  obtained  by  the  engineers  of  the 
Philadelphia  Bureau  of  Surveys.] 

THE  concrete  surfaces  shown  in  the  accompanying  photographs 
are  easily  obtained.    The  process  consists  in  completely  flush- 
ing the  face  against  the  form,  removing  the  form  after  the 
material  has  set  but  while  it  is  still  friable,  and  then  immedi- 
ately washing  and  rinsing  the  surface  with  water. 

The  washing  removes  the  film  of  cement  which  has  formed  against  the 
mold,  and  exposes  the  particles  of  sand  and  stone.  The  appearance  then 
depends  of  course  upon  the  character  of  the  aggregate  in  the  concrete  and 
the  uniformity  of  its  distribution  in  the  mixture.  As  in  well  mixed  con- 
crete the  cement  merely  fills  the  voids  between  the  grains  of  the  sand,  and 
the  sand  fills  the  voids  between  the  pebbles  or  particles  of  crushed  stone, 
the  cement  visible  in  this  finished  surface  is  so  small  a  percentage  that  it 
has  very  little  influence  on  the  color  of  the  work. 

A  convenient  means  of  securing  a  well  flushed  front  uniform  in  tex- 
ture is  to  make  a  fine  concrete  with  the  crushed  stone  or  pebbles  screened 
to  not  exceed  say  three-eighths  inch,  and  apply  it  to  the  face  form  with  a 
trowel  just  in  advance  of  the  body  concrete,  and  ram  the  concrete  into  it 
or  joggle  the  two  mixtures  together  so  as  to  ensure  an  intimate  union.  This 
fine  concrete,  or  granolithic  mixture  as  it  is  generally  called,  may  be  made 
of  different  colored  and  different  graded  aggregates  for  different  portions 
of  a  structure  to  compose  a  color  scheme. 

The  appearance  may  also  be  controlled  somewhat  by  the  extent  of  the 
washing,  for  if  the  work  be  done  at  the  right  time  the  washing  brush  can 
be  plied  to  remove  the  mortar  to  a  considerable  depth  between  the  stones, 
leaving  the  stone  in  a  very  decided  relief  and  producing  a  rough  coarse 
texture  which,  by  the  way,  seems  to  be  the  one  most  admired  by  the  ma- 
jority of  observers. 

The  time  to  be  allowed  for  setting  before  washing  must  be  determined 
with  regard  to  the  nature  of  the  cement  used  and  to  atmospheric  conditions. 
Quick-setting  cement  and  warm  weather  call  for  removal  of  form  within 
eight  or  ten  hours.  The  usual  practice  in  summer,  using  almost  any  of  the 
American  Portland  cements,  is  to  remove  the  forms  on  the  day  following 
the  deposit  of  the  concrete.  Of  course  this  must  not  be  done  with  the 

[104] 


A  SURFACE  FINISH  FOR  CONCRETE. 


FIG.   I.       EXAMPLE     OF    CONCRETE    COMPOSED    OF    I    PART    CEMENT,    2    PARTS    YELLOW     BANK 
SAND    AND    ?    PARTS    %-INCH    SCREENED    STONE.     ACTUAL    SIZE 


'iw^i^KiM 

:•.'  &fT  >  J'%"-  .*<«*   2 .  A'"  •"  k  \   *  y     ../    y  •  •/^*; 


FIG.   II.       PEBBLE    AND    SAND    CONCRETE    WITH    SCRUBBED    SURFACE    COMPOSED    OF    I     PART 
CEMENT,   Z    PARTS    BAR    SAND    AND    3    PARTS    J-I6-INCH    WHITE    PEBBLES.      ACTUAL    SIZE 


[105] 


REINFORCED  CONCRETE 


I 


FIG.   III.       SAND    AND    YELLOW    PEBBLE    CONCRETE    COMPOSED    OF    I    PART    CEMENT,   ^    PARTS 
BAR    SAND    AND    3    PARTS    SCREENED    YELLOW    PEPPLES.     ACTUAL    SIZE 


1! 

m- 


FIG.  IV.       GRANITE    GRIT    CONCRETE     COMPOSED     OF    I     PART     CEMENT,    2.    PARTS    BAR    SAND 
AND    l    PARTS    i<-INCH    GRANITE    GRIT.     ACTUAL    SIZE 


106] 


A  SURFACE  FINISH  FOR  CONCRETE. 


FIC-.  V.       EXAMPLE    OF    CEMENT    AND    SAND    MIXTURE    COMPOSED   OF    I 
PART    CEMENT    AND    2.    PARTS    B\R    SAND.      ACTUAL    M'/.h 


,.  :.;.#  ;^/.   -•  -4      ,   . 

FIG.   VI.       YELLOW    BAR    SAND    AND    CEMENT    COMPOSED    OF    I    PART    CEMENT    AND    j    PARTS 
YELLOW    BAR    SAND.       ACTUAL    SIZE 


[107] 


REINFORCED  CONCRETE 

under  or  supporting  portion  of  forms  for  arches  and  floors  where  the  con- 
crete is  subject  to  stress,  particularly  in  combination  with  reinforcement. 
Concrete  that  is  sufficiently  hard  to  sustain  more  compression  than  that  due 
to  the  superimposed  weight  of  a  few  of  its  own  layers  is  too  hard  to  wash. 
In  cool  weather  when  crystallization  proceeds  more  slowly,  the  washing 
is  practicable  two  or  even  three  days  after  laying,  and  in  cold  weather  a 
whole  week  has  been  found  not  too  long  to  leave  it  in  the  forms  when  a 
slow-setting  cement  has  been  used. 

If  it  should  happen  that  a  face  has  been  permitted  to  become  too  hard 
for  washing  With  a  brush,  the  film  can  be  rubbed  off  with  a  small  block  of 
wood  or  sandstone  with  a  copious  flow  of  water,  but  it  is,  of  course,  labor- 
ious and  it  cannot  well  be  carried  to  the  point  of  leaving  the  particles  of 
aggregate  in  appreciable  relief.  The  nearest  approach  to  the  washed  sur- 
face is  the  effect  produced  by  dressing  with  a  sharp  bush  hammer  and  then 
washing  with  muriatic  acid  diluted  one  half.  The  acid  should  be  well 
rinsed  off. 

If  the  height  of  the  wall  to  be  thus  treated  is  too  great  to  be  completed 
in  one  day  face  forms  must  be  constructed  to  facilitate  the  remova]  of  the 
planking  without  disturbing  the  studs  or  uprights.  This  is  easily  accom- 
plished by  setting  the  studs  8"  to  12"  away  from  the  face  line  and  support- 
ing the  planks  with  cleats  —say  2"Xi" — tacked  to  the  studs  and  the 
planks.  This  permits  the  lower  planks  to  be  removed  and  the  washing  done 
while  the  upper  planks  are  in  place  and  concrete  being  deposited.  With  the 
exercise  of  very  watchful  care  on  the  part  of  the  workmen  and  unremit- 
ting inspection  two  different  day's  work  can  be  joined  so  that  after  wash- 
ing the  joint  will  not  be  unsightly — even  scarcely  distinguishable,  but  such 
work  is  usually  not  obtainable  throughout  a  structure,  and  it  is  found  very 
easy  to  obtain  thoroughly  satisfactory  joints  by  indenting  horizontal 
grooves  at  regular  intervals  representing  courses,  and  finishing  each  clay's 
work  at  the  apex  of  a  groove.  These  indentations  are  made  by  means  of 
triangular  beads  on  the  face  forms.  Usually  the  bead  is  the  bevelled  edge 
of  a  strip  set  between  the  face  planks  and  lightly  secured  to  the  planks  with 
partly  driven  toe  nails  so  that,  if  desired,  a  plank  can  be  removed  indepen- 
dently of  the  bead  above  it,  the  bead  remaining  to  set  the  plank  upon  for 
the  next  course.  These  grooves  in  the  face  of  a  wall  improve  the  appear- 
ance by  relieving  the  blankness  of  a  large  area.  It  is  found  practicable  to 
prosecute  the  work  with  one  course  of  planks  where  the  capacity  of  the 
plant  for  one  day  is  equal  to  only  one  course  of  concrete.  In  this  way 
the  same  planks  have  been  used  for  many  different  courses  on  four  or 
rfiore  different  structures. 

The  cost  of  washing  depends  upon  the  degree  of  hardness  attained 
by  the  face.  If  it  be  taken  at  the  right  time  three  or  four  passages  of 
an  ordinary  house  scrubbing  brush  with  a  free  flow  of  water  from  a  hose 
or  sponge  will  be  all  that  is  required,  and  a  laborer  should  wash  say  one 
hundred  square  feet  in  an  hour  if  the  work  is  conveniently  accessible. 
[108] 


CONCRETE    BRIDGE    AT    GRAVER'S    LANE,    PHILADELPHIA,    WITH     SURFACE    TREATED    BY    THE 

QUIMBY    PROCESS 


CONCRETE    ABUTMENT    FOR    SEDGLEY    AVENUE    BRIDGE,    PHILADELPHIA,    WITH    SURFACE 
TREATED    BY    THE    QUIMBY    PROCESS 


REINFORCED  CONCRETE 

With  a  harder  surface,  such  as  it  is  likely  to  have  within  twenty-four 
hours  in  summer,  scraping  with  a  wire  brush  first  will  accelerate  the 
washing  which  may  then  require  from  two  to  five  hours  for  one  hundred 
square  feet.  Bush  hammering  will  cost  probably  from  five  to  ten  cents 
per  square  foot  according  to  the  quantity  and  the  outfit. 

This  wash  method  of  finishing  has  been  in  use  for  about  three  years, 
and  the  surfaces  are  quite  as  pleasing  after  the  lapse  of  time  as  when 
fresh.  As  yet  no  hair  or  surface  cracks  have  been  found  in  any  work 
that  was  washed,  which  is  doubtless  accounted  for  by  the  fact  that  the 
only  material  in  which  such  cracks  can  develop  is  removed  by  the  pro- 
cess. 

A  material  advantage  in  the  use  of  forms  that  are  removable  while 
the  concrete  is  green  is  found  in  the  opportunity  for  repairing  blem- 
ishes. Incidental  voids  can  be  filled  with  the  same  material  and  bulges 
can  be  rubbed  off  because  of  its  freshness  without  impairing  the  finish. 

The  accompanying  illustrations  are  from  photographs  of  specimens 
of  various  mixtures.  The  round  baluster  which  is  a  left-over  from 
a  bridge  is  composed  of  i  cement,  2  unscreened  yellow  bank  sand  and 
3  cleaned  1-4  inch  crushed  dark  stone.  The  square  baluster,  also  a  left- 
over— is  composed  of  I  cement  and  3  uncleaned  i -4-inch  crushed  dark 
stone,  the  stone  dust  forming  the  sand  portion.  The  mixture  was  used 
for  the  whole  body  of  the  baluster  in  each  case,  iron  molds  being  used, 
and  the  washing  done  within  twenty-four  hours.  The  six  cuts  repre- 
senting different  mixtures  as  labeled  show  the  actual  size  of  the  orig- 
inal. 

It  is  very  important  to  direct  the  reader's  attention  to  the  fact  in  all 
of  the  concrete  surfaces  shown  herewith  the  coarse  aggregate  projects 
in  low  relief.  It  may  appear  to  one  person  in  proper  form  while  to 
another  it  may  seem  sunken  or  intaglio,  as  though  the  surface  had 
formerly  been  incrusted  with  pebbles  and  sand,  which  had  washed 
away.  This  is  a  curious  optical  illusion  governed  by  the  positon  of 
the  light  as  it  falls  upon  the  page.  If  what  are  really  crushed  par- 
ticles of  stone  or  gravel  in  relief  should  appear  as  depressions,  turn 
the  picture  upside  down  or  in  proper  position  to  get  the  true  impression. 


[no] 


CONCRETE    BRIDGE    BALUSTER    TREATED    BY    QULMBY    PROCESS. 
I    PART    CEMENT,  }   PARTS  UNSCREENED   DARK  STONE  GRIT 


CONCRETE  BRIDGE  BALUSTER   SHOWING   QUIMBY   PROCESS.     I   PART  CEMENT,  2  PARTS 
YELLOW   BANK  SAND  AND  J  PARTS  DARK  STONE  GRIT 


VALUE  OF  CONCRETE  AS  A 
STRUCTURAL  MATERIAL 

In  this  symposium^  prominent  engineers  and  builders 

give  abundant  reasons  to  justify  its  use  in 

seeking    the    highest    development 

of  the  industrial  plant 

\It  would  be  extremely  difficult  in  this  day  to  find  a  plan  for  industrial 
plant  or  factory  in  which  the  use  of  concrete  in  some  form  is  not  contemplat- 
ed. The  chances  are  it  would  be  found  to  constitute  the  chief  features  of  the 
structure.  There  must  be  sound  and  economic  reasons  for  its  use.  In  work 
of  this  character,  the  structural  types  established  by  experience  as  best  adapt- 
ed to  a  purpose  are  not  lightly  thrust  aside  at  the  dictate  of  fancy  or  the  im- 
pulse to  experiment.  It  is,  nevertheless,  a  fact  that  in  a  day,  so  to  speak, 
known  and  tried  materials  have  been  supplanted  by  concrete. 

It  is  for  the  purpose  of  presenting  to  our  readers  in  concise  but  compre- 
hensive form  the  views  of  eminent  authorities  on  this  subject,  that  the  follow- 
ing contributions  have  been  solicited.  They  are  not  theoretical  conclusions, 
but  statements  based  upon  the  practical  work  and  observations  of  the  authors, 
to  whom  CEMENT  AGE  is  indebted  for  an  exceedingly  interesting  and  valuable 
feature  of  the  factory  number.} 


THE    ADVANTAGES    OF    REINFORCED 

CONCRETE 

By 
Emile    G.    Perrot 

[Ballinger  &  Perrot,  Architects  and  Engineers,  Philadelphia] 

When  it  is  remembered  that  for  heavy  construction,  where  large 
pieces  of  timber  form  the  principal  means  of  support,  the  quality  of 
material  has,  of  late  years,  steadily  depreciated  and  at  the  same  time 
become  more  scarce,  designers  of  industrial  plants  were  perforce  obliged 
to  look  about  for  some  substitute  that  would  permit  of  the  construction 
of  this  class  of  buildings  without  materially  adding  to  the  cost  and  at 
the  same  time  be  better  than  the  old  method  of  construction.  These 
conditions  we  find  happily  met  in  reinforced  concrete,  and  the  test  of 
years  has  proven  that  for  all  types  of  building,  and  especially  for  the 
[112] 


VALUE  OF  CONCRETE  AS  A  STRUCTURAL  MATERIAL 

factory  and  warehouse,  class,  this  method  of  construction  far  outweighs 
in  all  points,  the  older  and  less  durable  type  of  slow  burning  and  wood 
constructed  floors.  Not  only  for  floors  and  columns  is  reinforced  con- 
crete adaptable,  but  for  walls  as  well,  permitting  much  less  material  in 
the  wall,  while  it  gives  added  space  for  windows.  This  increases  the 
brilliancy  of  the  building,  which  is  a  most  important  feature  in  industrial 
plants. 

The  chief  points  in  favor  of  reinforced  concrete  are  : 

First :  Reinforced  concrete  becomes  stronger  with  age ;  slow  burn- 
ing becomes  weaker,  owing  to  the  rotting  of  timbers,  etc. 

Second:  Resistance  to  vibration,  increasing  the  life  of  and  lessen- 
ing repairs  to  machinery. 

Third :  Low  cost  of  insurance,  and  almost  entire  immunity  from 
fire,  thus  avoiding  loss  of  business  due  to  shut-down  of  plant. 

Fourth:  Cheap  materials  and  labor.  Materials  are  found  in  prac- 
tically every  locality. 


REINFORCED  CONCRETE  FOR FACTORY 
CONSTRUCTION 

By 
C.  A.  P.  Turner,  M.  Am.  Soc.  C.  E. 

While  reinforced  concrete  was  used  prior  to  steel  for  structural 
purposes,  it  is  only  of  late  years  that  it  has  come  into  extensive  use 
due  to  the  enterprise  of  the  Portland  cement  manufacturers  in  placing 
at  the  disposal  of  the  Constructing  engineer  a  material  of  reasonable 
cost,  reliable,  if  properly  handled,  and  which  bids  fair  to  supplant  struc- 
tural steel  in  the  construction  of  minor  engineering  works.  It  is,  then,  the 
question  of  cost  or  economy  which  has  brought  reinforced  concrete  into 
favor,  assisted  somewhat  by  the  well-known  advantages  of  permanence 
of  the  construction,  its  perfect  protection  of  the  steel  against  corrosion 
or  destruction  by  fire,  and  last,  but  by  no  means  least,  to  the  peace  of 
mind  of  the  builder,  the  avoidance  of  complex  shop  details,  and  the 
opportunity  for  the  annoying  little  errors  and  endless  delays  incident 
to  structural  steel  work. 

As  to  its  special  adaptability,  as  applied  to  factory  construction, 
we  must  consider  the  following  types  of  factories  or  manufacturing 
plants :  First,  those  which  are  one-story  mill  buildings,  with  long-span 
roofs:  for  these,  reinforced  concrete  cannot  compete,  for  the  main 
frame,  with  light  structural  trusses,  and  the  comparison  between  a  slab 
of  cinder  concrete  and  heavy  sheathing  is  in  favor  in  point  of  first  cost 
of  the  sheathing,  and  concrete  must  win  favor  on  its  merits  as  fire- 

[113] 


REIXFORCED  CONCRETE 

proof  construction.  Where  buildings  are  several  stories  in  height,  to 
carry  heavy  loads,  say  250  Ibs.  per  square  foot,  and  the  column  spacing 
is  from  16  to  19  feet,  or  more,  centers,  reinforced  concrete  can  compete, 
in  point  of  cost,  with  first-class  timber  construction,  while  structural 
steel  skeletons,  with  timber  floors,  are  much  more  expensive. 

The  advantages,  in  addition  to  low  first  cost  and  the  fireproof  char- 
acter of  the  material,  are  its  stiffness,  which  is  much  greater  than  steel 
or  timber  construction,  its  freedom  from  deterioration — a  good  concrete 
building  growing  stronger  for  many  years — and  the  rapidity  with  which 
it  may  be  erected.  There  is  little  or  no  delay  in  getting  cement  and  plain 
steel  rods  for  the  reinforcement,  which  is  quite  the  contrary  in  attempt- 
ing to  put  up  a  structural  steel  or  timber  frame  building.  In  the 
arrangements  for  the  shaft  supports,  it  is  not  quite  as  easy  to  make  the 
attachments  to  concrete  construction  as  to  the  timber  frame,  but  this 
difficulty  can  be  avoided  entirely  by  laying  out  the  arrangement  of  the 
shafting  and  machinery  in  advance,  and  casting  the  necessary  connec- 
tions in  the  concrete. 

As  regards  the  economy  of  construction,  reinforced  concrete,  in 
taking  the  place  of  timber  and  steel  frame,  as  is  usual  in  the  adaptation 
of  a  new  material  in  place  of  the  older  types,  h'as  been,  to  a  very  large 
extent,  influenced  by  former  practice  with  other  materials.  For  example, 
some  of  the  older  types  of  reinforced  concrete  construction  would,  at 
first  glance,  appear  similar  to  wood  construction.  A  building  put  up  in 
Milwaukee  ten  or  twelve  years  ago  had  a  floor  span  of  20  feet,  or  there- 
abouts, was  arranged  with  ribs  approximately  3!  or  4  ins.  by  16  ins. 
deep,  spaced  18  or  2O-inch  centers,, 4with  a  3-inch  floor  slab  on  top. 

A  little  computation  of  the  cost  of  centering  for  a  construction  of 
this  character  will  unquestionably  show  that  the  centering  cost  as 
much,  or  more,  than  the  reinforced  concrete,  in  fact  every  rib  or  break 
in  the  construction  is  expensive,  in  framing,  cutting  up  lumber  and 
using  up  time.  As  the  advantages  of  reinforcement  in  many  directions, 
in  a  composite  material  like  concrete,  become  better  understood,  a 
construction  which  takes  into  consideration  cutting  loose  entirely  from 
the  ideas  and  methods  which  govern  the  inherent  characteristics  of 
timber  or  structural  steel  frames,  will  become  more  generally  adopted, 
and  we  may  look  for  flat  slab  construction  without  ribs  to  obstruct 
light,  gather  dust  and  interfere  with  the  convenient  arrangement  of 
shafting  and  pulley  supports.  Such  construction  will  have  the  advantage 
in  view  of  the  thicker  slab  which  will  be  used,  of  more  uniform  stiff- 
ness, better  provision  for  temperature  stresses  or  concentrated  loads, 
be  more  pleasing  in  appearance,  more  economical  in  materials  and 
centering,  will  not  obstruct  light  with  ribs,  be  easier  kept  clean,  cost 
less  for  centering  and  require  a  smaller  amount  of  material  for  a  given 
strength,  as  the  necessary  increase  in  thickness  of  the  slab  will  not 
[114] 


VALUE  OF  COXCRETE  AS  A  STRUCTURAL  MATERIAL 

require  quite  as  much  material  as  is  at  the  present  time  put  into  rib 
construction. 

Evidently  this  construction  has  its  limits  of  economy.  For  very 
long  spans,  it  is  not  suitable,  but  for  spans  from  16  to  20  feet,  it  may 
be  used  to  advantage.  Such  spans  are  those  commonly  adopted  in 
warehouse  and  many  types  of  mill  and  factory  construction.  The 
illustrations  on  pages  328  'and  329  give  a  fair  idea  of  the  writer's  ideas 
of  this  type  of  construction.  The  first  is  a  photograph  of  the  rein- 
forcement before  the  concrete  was  poured,  showing  the  flat  slab  and 
the  arrangement  of  the  steel  reinforcement.  The  second  shows  a  test  load 
of  180  tons  placed  upon  a  slab  7^  to  7}  inches  thick,  in  the  rough,  with 
the  usual  inch  and  a  half  or  inch  and  three-quarters  of  strip  filling.  It 
should  be  observed  that  this  test  load  is  equal  to  the  weight  of  the 
heaviest  freight  locomotive  and  tender,  when  fully  coaled  and  the  tank 
filled  with  water,  and  that  it  occupied  a  space  but  little  greater  than 
half  that  which  would  be  taken  up  by  such  a  machine,  and  that  the 
deflection  of  the  floor  was  a  scant  quarter  of  an  inch  under  this  load. 

We  have  called  attention  to  the  fact  that  the  centering  is  no  small 
item  in  the  cost  of  construction,  cutting  up  and  wasting  lumber  in 
making  beam  boxes,  and  cutting  centering  between  slabs  is  an  item  that 
is  gradually  increasing  with  the  advance  in  price  of  lumber  and  labor. 
The  lumber  that  we  are  getting  in  this  section,  at  least,  for  centering, 
is  deteriorating  in  quality,  as  well  as  advancing  in  price,  and  it  is  only 
a  question  of  a  short  time,  in  the  writer's  judgment,  when  we  will  use 
steel  largely  for  centering;  in  fact,  we  have  already  commenced  to 
employ  metal  centering  and  are  finding  it  decidedly  economical,  as 
compared  with  cutting  up  sheathing. 

As  to  the  comparative  cost  of  concrete  and  first-class  timber  frame, 
the  same  contractor  bid  $10,000  less  on  reinforced  concrete  for  a  whole- 
sale and  factory  building  235x165  ft.,  seven  stories  in  height,  column 
spacing  18  feet  by  13  feet  4  inches,  capacity  of  floors  250  Ibs.  per  square 
foot,  to  be  tested  in  concrete  with  750  Ibs.  per  square  foot,  over  a  full 
panel. 


VIBRATIONS  OF  CONCRETE  FLOORS 

By 
E.  P.  Goodrich,  Mem.  Am.  Soc.  C.  E. 

[General  Manager  Underwriters  Engineering  and  Construction  Co.] 
The  reports  which  are  constantly  coming  in  with  regard  to  the  effect 
of  the  earthquake  and  fire  on  San  Francisco  buildings  are  showing 
more  and  more  clearly  the  hitherto  almost  unrecognized  superior 
advantages  of  reinforced  concrete  for  work  which  is  liable  to  the  shock  of 

[115] 


REINFORCED  CONCRETE 

earthquakes  and  to  the  devastating  effect  of  fire.  These  advantages  are 
described  as  being  "unrecognized,"  but  this  lack  of  recognition  was 
only  on  the  part  of  the  public,  and  those  who  had  not  had  actual  experi- 
ence with  regard  to  the  fireproofing  qualities  of  concrete,  or  who  had 
not  studied  this  subject,  and  the  somewhat  related  one  of  the  ability 
of  reinforced  concrete  work  to  withstand  shock.  Engineers  who  had 
given  this  subject  consideration  knew  that  the  little  concrete  work 
which  was  in  existence  in  San  Francisco  before  the  earthquake  would 
be  sure  to  take  the  palm,  when  compared  with  brick  and  terra  cotta 
and  that  it  would  become  the  material  recognized  as  being  the  best  for 
reconstruction  purposes. 

Tests  of  the  Vibration  of  Concrete 

Those  who  had  studied  the  subject  of  vibration  in  concrete  build- 
ings knew  its  value  from  that  point  of  view,  and  those  who  are  acquainted 
with  the  literature  on  the  subject  will  recall  the  results  of  the  tests  made 
by  the  engineers  of  the  Paris  and  Orleans  Railway  Co.  in  Paris,  in  which 
a  weight  was  dropped  from  a  given  height  on  a  floor  construction  made 
of  steel  beams  with  brick  arches,  and  the  amplitude  and  time  of  vibra- 
tion of  the  structure  noted.  Another  weight  twice  as  heavy  was  dropped 
from  a  weight  twice  as  great,  onto  a  reinforced  concrete  floor,  which 
weighed  only  60  per  cent,  per  square  foot  as  much  as  the  brick  floor, 
and  the  amplitude  of  vibration  was  only  one-fifth  as  much,  and  the 
vibration  lasted  only  one-third  as  long  as  in  the  case  of  the  steel  and 
brick  floor. 

The  New  York  Times  of  April  23,  (only  four  days  after  the  earth- 
quake,) commented  in  its  main  editorial  upon  the  description  given  by 
a  correspondent  of  the  method  after  which  the  Capitol  of  Mexico  had 
been  designed,  so  as  to  preclude  the  possibility  of  damage  from  earth- 
quake. The  edifice  is  to  be  erected  with  a  general  skeleton  of  steel 
columns  and  beams,  and  this  entire  skeleton  of  steel  will  be  completely 
embedded  in  a  concrete  made  of  a  light  volcanic  rock  resembling  coarse 
pumice  stone  mixed  with  the  proper  portions  of  cement.  The  concrete 
will  be  strong  enough  to  support  the  steel,  and  this  steel  will  form  a 
gigantic  basket  work  strong  enough  to  support  the  concrete,  and  pre- 
vent cracks  forming  under  strains  due  to  terrestrial  disturbances. 

Long  before  the  San  Francisco  earthquake,  the  Japanese  had  noted 
the  marked  advantages  inhering  in  reinforced  concrete,  and  it  is  under- 
stood that  engineers  from  that  progressive  country  have  instituted  a 
series  of  tests,  in  which  small  structures  are  mounted  upon  tables  cap- 
able of  being  vibrated  in  the  same  way  in  which  an  earthquake  would 
shake  the  same  structure,  and  the  effect  of  various  kinds  and  durations 
of  shock  carefully  studied. 

The  survival  after  earthquake  and  fire  of  the  walls  of  the  Palace 
[116] 


VALUE  OF  COXCRETE  AS  A  STRUCTURAL  MATERIAL 

Hotel  in  San  Francisco  is  in  a  large  measure  a  demonstration  of  the 
value  of  reinforced  work  in  the  withstanding  of  earthquakes.  In  it  the 
brick  walls  are  tied  together  by  embedded  iron  rods,  so  that  the  work 
was  practically  ''reinforced  brick  work,"  in  a  sense  somewhat  like  "rein- 
forced concrete/'  It  is  evident  that  even  with  the  best  of  workmanship, 
since  brick  work  is  made  of  separate  blocks,  cemented  together,  it  can- 
not begin  to  possess  the  advantages  of  concrete,  properly  reinforced,  in 
which  the  whole  mass,  when  properly  mixed  and  deposited,  becomes  a 
monolithic  structure. 

The  Strength  of  Reinforced  Concrete  Floors 

It  would  seem  that  such  a  demonstration,  together  with  the  appar- 
ently immune  condition  of  the  large  number  of  concrete  floors  in  San 
Francisco  still  intact,  could  leave  no  room  for  doubt  as  to  the  great 
superiority  of  reinforced  concrete  for  the  rebuilding  of  San  Francisco, 
with  particular  regard  to  the  possibilities  of  future  earthquakes.  A  test 
to  destruction  of  several  of  the  surviving  concrete  floor  slabs  would  be 
a  most  instructive  experiment,  especially  when  studied  in  the  light  of 
their  original  theoretical  supporting  power.  Long  before  any  reports 
were  received,  and  immediately  after  the  earthquake  and  fire,  many 
engineering  periodicals  prophesied  that  concrete  would  show  itself  the 
best  material  to  be  used  in  the  rebuilding  of  the  stricken  city,  and  it  is 
believed  that  their  prophecies  have  been  proven  very  likely  of  fulfill- 
ment, to  say  the  least. 

As  to  concrete,  on  the  side  of  a  fire-protecting  or  fire-retarding 
material,  the  reports  being  made  to  the  insurance  companies  stand  with- 
out question.  The  experts  in  fire  protection  connected  with  the  numer- 
ous insurance  companies  long  ago  recognized  the  value  of  reinforced 
concrete  buildings  from  an  insurance  standpoint,  and  at  the  present 
time  probably  the  lowest  insurance  rates  to  be  found  anywhere  -in  the 
United  States  on  mercantile  buildings  are  on  a  series  of  tenant  factory 
buildings  in  Brooklyn,  New  York,  built  of  reinforced  concrete  with 
sprinkler  equipment,  wire  glass  supported  in  metal  frames  throughout, 
etc.  Without  question,  that  is  the  type  which  should  be  adopted  in 
San  Francisco. 

The  attention  of  fire  underwriters  has  been  particularly  called  by 
their  consulting  engineers  to  the  wonderful  ability  of  concrete  to  pro- 
tect steel  against  the  effects  of  heat,  and  Mr.  S.  A.  Reed  in  reporting  to 
the  Committee  of  Twenty,  at  a  late  date,  noted  particularly  the  superi- 
ority of  solid  concrete  column  protection  over  any  form  of  fireproofmg 
which  contained  an  air  space.  Quiet  air  has  always  been  considered 
as  the  most  perfect  insulator  obtainable,  but  such  instances  as  occurred 
in  tjie  basement  of  the  Aronson  Building,  in  which  columns  buckled, 
which  were  protected  with  air  space,  while  others  in  the  same 

[117] 


REINFORCED  CONCRETE 

basement  withstood  all  strains  where  encased  in  solid  concrete,  is  ample 
proof  of  the  value  of  the  latter  method  of  fireproofing.  Mr.  Reed,  in 
his  report,  also  calls  especial  attention  to  the  great  heat  probable  in 
the  Bush  Street  Telephone  Building,  and  how  perfectly  the  steel  columns 
were  protected,  and  even  probably  supported  by  the  solid  concrete 
encasement,  even  though  the  temperature  of  the  column  steel  may  have 
been  so  high  as  actually  to  soften  the  structural  work. 

It  thus  appears  that  before  the  catastrophe  occurred  which  devas- 
tated San  Francisco,  engineers  all  over  the  world  were  turning  to  rein- 
forced concrete  as  the  solution  of  their  difficulties  with  regard  to  both 
earthquakes  and  fires. 


CONCRETE  IS   FIREPROOF,   RIGID   AND 

PERMANENT 

By 
J.  R.  Worcester,  M.  Am.  Soc.  C.  E. 

Concerning  the  value  of  reinforced  concrete  for  factory  buildings,  I 
would  say  that  there  is  no  question  as  to  its  manifest  advantages  in  incombus- 
tibility, rigidity,  and  permanence. 

There  are,  however,  some  disadvantages  in  its  use  which  must  be  taken 
into  consideration  in  recommending  this  material.  These  are  the  treatment  of 
outside  walls  to  insure  freedom  from  cracks  and  a  pleasing  appearance ;  the 
size  of  interior  columns  where  there  are  a  number  of  stories  to  be  supported ; 
and  the  increased  weight  upon  the  foundations  where  the  ground  is  soft. 

It  is  probable  that  as  time  goes  on,  we  shall  learn  more  with  regard  to 
methods  of  overcoming  the  above  mentioned  disadvantages,  but  now 
there  is  plenty  of  chance  for  study  along  this  line. 


THE  UTILITY  OF  CONCRETE 

By 
Henry  H.  Quimby,  M.  Am.  Soc.  C.  E. 

[Engineer  of  Bridges,  Bureau  of  Surveys,  City  of  Philadelphia.] 

Good  concrete  can  be  obtained  at  a  price  that  permits  us  to  use  it  in  equal 
volume  instead  of  a  cheap  class  of  stone  or  brick  masonry — to  which  it  is  pro- 
bably always  preferable — and  induces  us  to  use  it  in  place  of  a  superior  class 
of  masonry.  Its  character  enables  us  to  make  a  more  economical  and  effect- 
ive distribution  of  our  building  material,  to  the  saving  of  a  considerable  pro- 
portion of  the  yardage. 

The  twin  virtues  of  convenience  and  economy  are  attributes  to  which 
most  credit  is  due  for  its  popularity  as  a  material  of  construction.  They  are 
[118] 


VALUE  OF  CONCRETE  AS  A  STRUCTURAL  MATERIAL 

~\ 

also  responsible  for  its  use  by  unskilled  designers  and  constructors  and  for 
some  consequently  lamentable  failures.  Because  probably  of  insufficient 
scientific  knowledge,  and  possibly  of  rank  dishonesty,  and  certainly  of  gross 
carelessness  on  the  part  of  designers,  contractors  and  workmen,  uniform  and 
dependable  quality  is  not  among  its  undisputed  virtues.  Unremitting  vigi- 
lance of  intelligent  supervision  is  more  vital  than  the  quality  of  the  cement, 
but  it  can  be  secured  and  a  sufficiently  satisfactory  grade  of  quality  assured 
for  safe  designing. 

Like  all  other  good  things,  it  has  limitations  and  when  these  are  over- 
stretched disaster  follows  and  conservative  designers  continue  to  hesitate. 
But  it  is  scarcely  a  dozen  years  since  some  of  the  most  responsible  engineers 
looked  askance  at  steel,  even  with  its  price  lower  than  that  of  wrought  iron, 
using  it  only  long  after  their  bolder  brethren  had  offered  to  manufacturers 
ample  opportunity  to  demonstrate  its  reliability.  So  concrete  will  win 
as  it  continues  to  stand  up  to  its  work  and  as  its  remarkable  adaptability 
becomes  more  widely  recognized. 

Good  concrete  has  fair  compressive  strength,  usually  all  that  is  needed, 
though  it  is  not  comparable  with  that  of  good  stone,  but  is  comparable  with 
that  of  well  built  stone  masonry.  There  is  no  longer  any  doubt  of  its  excel- 
lent fire-resisting  quality  when  made  with  a  proper  aggregate.  Its  weak- 
ness is  in  its  low  tenacity  and  consequent  low  shearing  value.  The  meas- 
ure of  resistance  to  cracking  of  well  bonded  stone  masonry  is  that  of  the 
stone  itself,  while  the  resistance  of  concrete  to  cracking  is  principally  the 
adhesion  of  the  mortar  to  the  surface  of  the  stone  particles  which  constitutes 
the  cohesion  of  the  mass,  the  crushed  stone  being  too  small  to  furnish  any 
appreciable  bond.  The  liability  to  cracks  rupturing  the  body  impairing  the 
structure  is  the  principal  cause  of  such  distrust  of  the  material  as  exists 
among  engineers  and  architects.  A  judicious  use  of  steel  rods  can  gener- 
ally be  depended  upon  to  counteract  the  tendency  to  cracking  for  the  rods 
can  be  placed  so  as  to  provide  the  necessary  resistance  to  disrupting  forces 
whether  they  be  internal  stresses  produced  by  shrinkage,  or  external  ones 
caused  by  unequal  settlement  of  foundation  or  by  direct  loads. 

Some  dislike  of  concrete  is  due  to  the  unsatisfactory  surface  finish  so 
commonly  given  to  it,  which  is  an  application  of  neat  cement  brushed 
on  like  paint  or  rubbed  on  with  a  float,  and,  while  sufficiently  uniform 
to  be  pleasing  to  the  eye,  becomes  very  unsightly  in  a  short  time  through  the 
development  of  surface  cracks  and  their  absorption  of  moisture,  and  some- 
times even  the  peeling  of  the  coat.  This  condition  can  be  avoided  and  the 
objection  removed  by  the  more  modern  method  of  finishing  the  surface  by 
removing  the  film  that  forms  against  the  mold.  This  can  be  done  at  very 
little  cost  in  most  cases  by  taking  the  forms  away  while  the  concrete  is  still 
green  and  washing  ofY  the  film  with  a  brush  and  water,  and  when  the  forms 
can  not  be  removed  until  the  work  is  hard  the  film  can  be  removed  by  tool- 
ing-bushhammering,  which,  on  a  good  sized  job,  will  cost  about  five  cents 

[119] 


REINFORCED  CONCRETE 

per  square  foot  of  surface.  This  treatment  exposes  the  sand  and  grit  show- 
ing the  actual  texture  of  the  material  giving  it  the  appearance  of  stone,  and 
as  surface  cracks  never  appear  in  it,  should  influence  the  adoption  of  con- 
crete in  construction  where  appearance  is  a  consideration. 


ADVANTAGES   MORE   THAN   OFFSET 
OBJECTIONS   TO   CONCRETE 

By 

Dean    &   Main 
[Consulting  Engineers,  Boston,  Mass.] 

Because  of  the  inflexibility  of  the  construction  and  the  trouble  and 
expenses  involved  in  adapting  it  to  changed  conditions,  the  progress  of  rein- 
forced concrete  in  supplanting  slow  burning  construction  in  textile  plants, 
where  reorganization  and  changes  to  meet  new  methods  must  continually 
take  place,  will  be  slow.  Among  the  chief  difficulties  encountered  may 
be  mentioned :  Changes  in  the  location  of  shafting ;  proper  fastenings  and 
supports  for  machines  when  re-located,  and  the  tiresome  effects  upon 
employes  who  are  obliged  to  stand  or  walk  upon  such  a  rigid  and  inflex- 
ible surface  for  any  length  of  time.  On  the  other  hand,  the  growing- 
scarcity  and  the  corresponding  increase  of  cost  of  lumber,  suitable  for 
mill  construction,  as  well  as  reduced  risks  from  fire,  will  tend  to  bring 
the  construction  into  more  general  use,  in  spite  of  the  obstacles  before 
named. 

With  the  existing  high  cost  of  brick  and  lumber,  the  cost  of  rein- 
forced concrete  compares  favorably  with  that  of  slow  burning  construction, 
the  former  probably  being  no  more  than  five  per  cent,  in  excess  in  ordinary 
cases.  In  cases  where  duplication  of  forms  enter  to  any  extent,  and  where 
sprinkler  systems  may  be  omitted,  this  excess  is  often  reduced  to  nil. 

As  affording  a  brief  idea  of  the  use  of  reinforced  concrete  for  indus- 
trial purposes,  we  offer  a  partial  list  of  work  we  have  designed  and  placed 
under  construction  this  season : 

American  Woolen  Co.  dye  house,  Lawrence,  Mass.  A  building  530 
ft.  long,  in  ft.  wide,  designed  for  six  stories.  The  adaptability  and  advan- 
tages found  for  concrete  construction  were :  Saving  of  20  feet  of  back- 
fill, as  well  as  deep  foundations;  immunity  against  deterioration  caused 
by  dampness  and  acids ;  heavy  concentrated  loads  on  beams  and  floors, 
easily  cared  for  by  braces  molded  between  beams  and  columns. 

Lawrence  Duck  Co.  building,  designed  for  storage  and  textile  pur- 
poses. This  structure  is  188  ft.  long,  65  ft.  wide,  five  stories  high,  with 
girders  over  existing  flume  carrying  building  and  tower  walls.  The 
advantages  are:  Avoidance  of  deep  foundations,  reduced  cost,  making 
renewal  of  flume  easy ;  more  durable  than  steel  beams  in  damp  locations. 
[120] 


VALUE  OF^CONCRETE  AS  A  STRUCTURAL  MATERIAL 

The  Simonds  Manufacturing  Co.  building,  Chicago,  111.  Construc- 
tion work  comprised  the  office  and  an  extension  of  the  manufacturing- 
building. 

The  Rosamond  Woolen  Co.  mill,  at  Almonte,  Ontario.  The  building 
is  a  weaving  mill,  one  story,  208  ft.  long,  75  ft.  wide.  The  advantage  was 
reduced  cost  over  masonry  walls ;  equally  adapted  to  retard  radiation. 

Dominion  Textile  Co.  plant,  Montreal,  Can.  Operation  consists  of 
a  cotton  storage  warehouse,  120  ft.  long,  100  ft.  wide,  eight  stories.  (Build- 
ing now  under  advisement.) 

The  Woo4  Worsted  Mills,  Lawrence,  Mass.  This  plant  includes  the 
entrance  building,  85x35^.,  columns,  steps,  floors,  roof,  and  balustrades, 
wool  scouring  and  wet  finishing  departments,  242x119  ft.,  reinforced  con- 
crete floors  with  supporting  columns,  also  columns  and  beams  for  floors 
above.  The  dyeing  department  is  176x119  ft.,  with  floor,  columns,  beams 
and  braces  for  a  32-ft.  story.  The  power  house  is  144x75  ft.,  reinforced 
concrete  roof  and  purlins.  The  boiler  house  is  270x31  ft.,  concrete  floors, 
beams  and  columns.  We  might  also  cite  a  miscellaneous  lot  of  concrete 
work  connected  with  this  mill,  consisting  of  two-foot  bridges,  trucking 
passageway,  418x18.  ft.,  toilet  room  floors,  wire  towers,  pipes  and  wire 
tunnels,  4O,ooo-gallon  water  tank,  1,700  linear  feet  of  hot  air  ducts,  etc. 

The  Penman  Manufacturing  Co.  plant,  Paris,  Ontario,  includes  200 
feet  of  headrace,  no  feet  of  tailrace,  and  floor  of  wheel-room. 

At  the  W.  F.  Rutter  &  Co.  plant,  Lawrence,  Mass.,  a  pipe  shop  60  ft. 
long,  27  ft.  wide ;  floor  and  supporting  columns,  designed  for  loads  of 
700  Ibs.  per  sq.  ft.  of  floor  surface. 


REINFORCED  CONCRETE  IN  MANUFAC- 
TURING  PLANTS 

By 
Leonard    C.    Wason 

[Aberthaw  Company,  Concrete  Engineers  and  Contractors,  Boston.] 

The  large  and  diversified  use  of  reinforced  concrete  in  mill  con- 
struction in  the  past  has  been  very  gratifying  to  those  interested  in  the 
design  and  building  of  this  type  of  structure.  But  the  very  rapid  increase 
in  its  use,  this  year,  has  been  a  great  surprise,  and  unlocked  for  by  the 
writer,  although  closely  identified  with  this  industry. 

Especially  noteworthy  is  the  fact  that  the  initiative  has  in  every  case 
been  taken  by  the  mill  owners  themselves,  who,  without  technical  knowl- 
edge of  the  material,  have  recognized  its  merits  and  desired  its  use. 

Within  the  writer's  personal  practice,  reinforced  concrete  has  been 
used  "either  for  floors  or  for  the  entire  structure  of  wood  pulp  and  linen 

[121] 


REINFORCED  CONCRETE 

rag  paper  mills,  chemical  works,  wool  scouring,  dyehouses,  laundries,  ice 
cream  and  soap  factories,  where  waterproof  and  rotproof  floors  were 
needed,  both  for  the  lightest  and  for  heavy  loads;  also  where  dry,  dustless 
floors  were  wanted,  as  in  jewelry,  spectacle,  textile  and  mills,  hardware, 
machine  foundry,  and  paint  shops,  where  live  loads  varied  from  50  to 
800  Ibs.  per  sq.  ft.  It  has  been  used  for  many  other  manufacturing  pur- 
poses, but  the  above  enumerated  list  is  sufficiently  diversified  to  show  that 
it  is  suitable  for  every  type  of  manufacturing  building. 

Inasmuch  as  in  the  majority  of  these  mills,  cost  was  the  prime  con- 
sideration, it  is  clear  that  reinforced  concrete  can  compete  with  the  older 
types  of  mill  construction ;  not  in  every  case  with  light  loads  because  this 
material  is  especially  adapted  to  heavy  loads,  and  therein  the  greatest  econ- 
omy can  be  obtained,  but,  all  advantages  considered,  then  its  net  econ- 
omy in  its  use. 

In  adapting  this  material  to  factory  use,  there  is  greater  latitude 
than  is  possible  with  brick  and  wood  in  the  design  of  the  building,  as 
floors  can  be  built  with  spans  varying  from  5  to  50  ft.,  and  loads  from  50 
to  1,000  Ibs.  per  sq.  ft.;  and  the  walls  may  either  be  piers  and  beams,  the 
space  between  being  filled  in  by  thin  curtain  walls  and  windows,  or  it  may 
be  a  solid  earing  wall  throughout. 

Floor  finish  may  be  granolithic,  asphalt,  wood  or  other  material  as 
desired  for  special  purposes.  Arrangements  can  easily  be  made  for  the 
support  of  line  shafting  and  machinery  from  walls,  columns  or  ceilings ; 
and  on  account  of  the  rigidity  of  the  reinforced  concrete  construction, 
which  is  one  of  its  essential  features,  there  is  absence  of  vibration  in  the 
building,  which  is  considered  a  desirable  feature  by  the  manufacturing  cor- 
porations. 

Referring  briefly  to  details  of  design,  a  reinforced  footing  enables 
us  to  get  a  large  spread  on  the  ground,  thereby  avoiding  dangerous 
settlement  with  a  very  limited  depth  of  excavation,  and  economy  is  gained 
by  the  saving  of  excavation,  the  small  amount  of  material  in  the  footing, 
and  frequently  by  the  avoidance  of  pumping  ground  water.  The  writer 
prefers  footings  octagonal  in  plan,  bars  running  in  two  principal  directions, 
with  a  few  running  diagonally  to  support  the  small  between  the  two  pre- 
vious sets. 

Columns  may  be  kept  of  reasonable  dimensions  by  using  rich  mix- 
tures. The  writer  has  used  as  rich  as  I  part  cement  to  i  part  stone,  with 
a  working  stress  of  1,200  Ibs.  per  sq.  ft.  at  the  age  of  one  month.  This 
same  mixture  would  have  to  be  used  through  the  thickness  of  a  floor,  as 
well  as  in  a  column,  in  order  to  obtain  necessary  strength.  Steel  bars  are 
used  as  a  precaution  against  flecture  only,  being  set  vertically,  one  near  each 
corner.  If  used  to  carry  load  in  connection  with  concrete,  their  stress  is 
so  low  as  to  destroy  economy.  .Hooped  columns  should  never  be  used 
because  when  built  with  hoops  these  are  never  brought  into  stress,  because 

*.•  - - 


VALUE  OF  CONCRETE  AS  A  STRUCTURAL  MATERIAL 

the  concrete,  in  setting,  has  a  tendency  to  shrink,  and  in  order  to  bring 
the  hoops  to  a  stress  which  makes  them  carry  part  of  the  vertical  load, 
the  concrete  must  be  stressed  way  beyond  its  safe  working  limits,  which 
of  course  should  never  be  done. 

In  floors  of  long  span,  the  writer,  six  years  ago,  made  a  very  careful 
analysis  of  the  spacing  for  maximum  economy,  considering  all  the  elements 
of  design,  cost  of  lumber,  concrete,  carpenter  and  concrete  labor.  Three 
feet  from  center  to  center  of  beams  was  then  found  to  give  maximum 
economy.  Under  existing  conditions,  this  would  be  somewhat  increased, 
probably  approaching  four  feet.  In  mill  construction,  this  spacing,  how- 
ever, is  more  likely  to  be  determined  by  the  conditions  of  design  of  mill 
than  by  those  of  maximum  economy  of  floor.  However,  the  difference 
in  cost  for  spacings  of  eight  to  ten  feet  with  a  flat  slab  between,  which  is 
common  in  mill  construction,  does  not  increase  the  cost  to  a  prohibitive 
amount. 

So  much  has  already  been  said  on  the  detail  of  beam  design,  both 
in  theory  and  practice,  it  is  unnecessary  to  add  more  to  the  discussion 
within  the  limits  of  this  article.  Every  week  produces  new  examples  of 
the  application  of  reinforced  concrete  to  mill  construction  and  adds  to 
the  advantages  shown  by  experience,  until,  to-day,  considering  both  first 
cost,  maintenance,  and  the  special  requirements  of  the  mill  construction, 
the  number  of  industries  to  which  this  material  cannot  be  profitably  applied 
are  exceedingly  few. 

This  subject  would  not  be  complete  without  reference  to  the  exten- 
sive use  of  reinforced  concrete  at  the  power  development  end  of  the  manu- 
facturing plant.  Some  of  the  largest  chimneys  now  in  use  are  of  rein- 
forced concrete,  and  some  of  unusual  design  as  a  spark  arrester  where 
the  chimney  rests  on  the  roof  of  a  chamber  elevated  high  in  air,  have  been 
successfully  built. 

Gravity  dams,  head  gates,  and  pentstocks  are  coming  into  such  gen- 
eral use  as  to  require  no  extended  description.  Their  economy  and  sta- 
bility are  far  greater  than  the  solid  type  of  dam  construction,  and  are 
entirely  watertight. 


CONCRETE    IN    BUILDING 
CONSTRUCTION 

By 
E.  S.  Lamed,  C.  E. 

[Member    American    Society    for    Testing    Materials   and  Cement 

Users'    Association.] 

,The  present  extensive  use  of  this  material  is  the  direct  outcome  of 
conservative,    patient    and   persevering   efforts    of    constructing^  _engineers. 

UNIVERSITY  OF  ^ 

TMEKT  OP  CIVIL 


REINFORCED  CONCRETE 

The  many  advantages  of  reinforced  concrete  have  only  recently  come  to 
be  generally  recognized.  The  use  of  the  material,  in  the  infancy  of  this 
industry,  was  not  only  a  question  of  its  relative  economy,  but  also  depended 
upon  the  capacity  of  architects  and  engineers  to  design  for  the  many  con- 
ditions that  must  be  successfully  met. 

Happily,  and  to  the  great  and  everlasting  credit  of  the  pioneers,  the 
first  example  of  this  type  of  construction  proved  successful  from  a  struc- 
tural standpoint,  and  the  influence  of  this  work  has  gained  weight  with 
time,  and  for  several  years  past  the  material  has  been  recognized  not 
only  as  a  structural  possibility,  but  its  more  extensive  and  universal  use 
has  only  been  limited  by  natural  and  commercial  conditions. 

Architects  and  constructing  engineers  are  coming  generally  to  recog- 
nize the  necessity  of  equipping  themselves  for  this  class  of  construction, 
but,  of  course,  until  this  is  accomplished,  many  will  be  obliged  to  design 
in,  and  use  other  materials  until  they  feel  competent  to  use  concrete. 

It  seems  to  the  writer  that  the  general  public,  in  their  demand  for 
concrete  construction,  are  considerably  in  advance  of  the  professions 
directly  interested,  and  in  many  cases  are  greatly  disappointed  to  find  their 
architects  unprepared  for  the  work  desired.  This  is  further  emphasized 
by  the  fact  that  many  examples  of  concrete  construction  it:  progress  to-day 
are  modifications  for  designs  in  stone,  brick,  timber  and  steel.  The 
specialty  companies  engaged  in  concrete  building  construction  have  found 
it  necessary  to  employ  specially  trained  technical  men  to  submit  designs 
and  prepare  details  for  the  approval  and  acceptance  of  architects,  and 
during  the  past  year  these  companies  have  been  so  overloaded  with  work 
that  they  have  been  obliged  to  turn  aside  many  pressing  inquiries,  that 
under  the  circumstances  could  only  be  met  by  contractors  experienced  in 
the  old  style  construction. 

It  must  be  conceded  that  the  enormous  growth  in  the  use  of  reinforced 
concrete  consturction  is  largely  due  to  the  influence  of  these  specialty 
companies,  who  have  at  their  command  men  trained  in  the  technique  and 
an  organization  experienced  in  the  handling  of  this  material. 

In  the  past  few  years,  it  has  been  found  that  municipal  building  com- 
missions have  through  their  inertia  placed  many  obstacles  in  the  way  of 
the  more  general  adoption  of  this  style  of  construction.  In  Boston  to-day 
the  building  laws  recognize,  to  a  very  limited  extent,  concrete  for  building 
constructon,  yet  for  several  years  past,  by  referring  requests  for  permits 
to  construct  in  concrete  to  the  Board  of  Appeal,  approval  has,  without 
exception,  been  given,  and  many  notable  examples  of  reinforced  concrete 
construction  may  be  found  in  the  city  to-day. 

Among  the   many   special   utility   applications   of   reinforced   concrete 

construction   may  be   cited   buildings   for   general    factory   and    warehouse 

construction,    cold    storage,   markets,   packing   and    slaughter    houses,    the 

advantage  in  the  material  being  found  not  alone  in  its  fireproof  qualities 

[124] 


VALUE  OF  CONCRETE  AS  A  STRUCTURAL  MATERIAL 

and  great  carrying  capacity  in  the  floor  construction,  but  also  in  its  clean- 
liness and  sanitary  conditions. 

The  superiority  of  concrete,  in  exposure  to  conflagrations  and  earth- 
quake disturbances,  has  been  so  emphasized  in  the  experience  of  Bal- 
timore, Rochester  and  San  Francisco  that  to-day  no  doubt  remains  in  the 
minds  of  experienced  and  discriminating  observers  and  its  extensive  fur- 
ther use  is  sure. 

Where  fire  risks  are  great  and  the  value  of  merchandise  carried  on 
the  different  floors  of  large  retail,  wholesale  and  storage  mercantile  estab- 
lishments is  important,  the  value  of  concrete  floors  which  are  essentially 
waterproof,  has  been  demonstrated  in  localizing  damage  due  to  fire  and 
water,  and  its  use  for  floor  construction  alone  will  afford  large  and  grow- 
ing opportunities  for  experienced  construction  companies  in  work  of  this 
nature. 

Much  has  been  accomplished  in  the  past  few  years  tending  to  reduce 
the  cost  of  concrete  construction  through  the  simplicity  of  design  and  erec- 
tion of  forms,  yet  much  remains  to  be  done,  and  progress  is  constantly 
being  made  in  this  direction. 

Among  the  more  conservative  construction  engineers,  we  find  a  belief 
that  it  is  difficult  to  secure  satisfactory  and  artistic  treatment  of  exterior 
surfaces.  This,  to  some  degree,  is  warranted,  but  is  chiefly  due  to  the 
inexperience  of  contractors  or  engineers  themselves  in  this  department  of 
the  work.  It  is  generally  agreed  that  imitation  should  not  be  attempted, 
and  that  concrete  structures  should  be  given  a  treatment  original,  simple, 
and  in  entire  keeping  with  the  nature  of  the  material  itself,  by  the  careful 
selection  of  aggregates,  care  in  the  proportioning,  mixing  and  placing,  the 
use  of  pneumatic  tools,  the  sand  blast  or  the  mason's  float  trowel,  and  in 
combination  with  ornate  and  colored  tiles,  the  exterior  surfaces  of  build- 
ings can  be  given  a  finish  harmonious  and  pleasing  to  the  eye,  and  artistic 
to  a  degree  that  will  excite  a  general  desire  for  this  material,  not  alone  for 
mercantile  and  manufacturing  uses,  but  for  residential  purposes  as  well. 

In  considering  the  cost  of  concrete  construction,  architects  and  engi- 
neers have  oftentimes  been  deceived  by  the  apparent  saving  resulting  from 
lean  mixtures.  The  cost  of  cement  per  cubic  foot  or  cubic  yard  of  con- 
crete is  relatively  small  compared  with  its  cost  in  the  completed  work, 
and  the  many  advantages  of  the  rich  mixture  of  cement  in  adding  to  the 
compressive  strength  of  the  material,  its  fireproof  and  waterproof  qual- 
ities, and  in  overcoming  the  inequalities  of  imperfect  mixing  and  placing, 
are  now  coming  to  be  appreciated. 

It  has  always  seemed  to  the  writer  curious  that  mechanical  mixing 
of  concrete  should  have  been  brought  about  more  through  the  influence  of 
contractors  and  the  manufacturers  of  mechanical  mixers  than  the  demand 
of  engineers  and  architects  Ordinary  hand-mixing  of  concrete  is  at  best 
imperfect,  and  so  many  different  systems  of  combining  the  materials  are 

[125] 


REINFORCED  CONCRETE 

in  use  to-day  that  uniform  results  could  not  be  expected.  For  light  work 
and  reinforced  concrete  work  in  particular,  mechanical  mixing  should  be 
insisted  upon.  For  in  combining  cement,  sand  and  stone,  and  reducing 
to  a  plastic  condition,  it  is  necessary  to  mix  not  only  thoroughly  but  vig- 
orously, as  only  in  this  way  can  the  cement  and  sand  which  forms  the  bind- 
ing medium  be  brought  intimately  together. 

In  general,  competent  inspection,  independent  of  the  contractors  inter- 
ested, should  be  encouraged  in  all  concrete  construction,  not  only  to  see 
that  the  materials  are  properly  proportioned,  mixed  and  placed,  but  also 
to  be  prepared  to  report  to  the  designing  architect  any  conditions  that 
may  arise  which  call  for  special  treatment.  . 

The  value  of  cooperative  work,  such  as  has  been  inaugurated  by  the 
American  Society  of  Civil  Engineers  associated  with  the  American  Society 
for  Testing  Materials,  and  Railway  Engineering  and  Maintenance  of  Way 
Association,  together  with  the  Association  of  American  Portland  Cement 
Manufacturers  cannot  be  overestimated. 

The  assistance  of  the  United  States  Government  in  the  investigations 
and  experiments  now  in  progress  will  give  the  results  obtained  a 
significance  and  value  far  exceeding  anything  that  has  yet  been  under- 
taken, and  of  course  it  must  be  recognized  that  the  subject  cannot  be 
disposed  of  in  a  short  time,  but  it  is  believed  that  the  results  will  lead 
to  a  gradual  standardization  of  work  that  will  prove  beneficial  to  all 
interests  concerned. 

The  value  of  National  bodies  interested  in  the  use  of  cement  must 
also  be  recognized,  and  contractors,  architects  and  engineers  would  find  it 
greatly  to  their  advantage  to  be  affiliated  with  such  organizations  and  bene- 
fit in  the  exchange  of  ideas. 

Nothing  in  labor  conditions  can  be  advanced  to  the  detriment  of  con- 
crete construction.  Common  labor,  under4  competent  and  experienced 
supervision,  can  perform  the  work  with  entire  success,  and  while  it  is 
believed  and  hoped  that  men  specially  trained  in  this  work  will  increase 
in  numbers  and  receive  a  just  and  fair  compensation,  it  does  not  seem 
likely  that  the  work  will  ever  come  under  the  domination  of  trades  unions 
or  be  subject  to  the  delays  of  sympathetic  strikes. 

The  writer  would  throw  out  the  suggestion  to  intending  buiders,  that 
the  removal  of  reinforced  concrete  structures  will  not  prove  an  easy  taskr 
and  on  city  property  in  particular,  where  the  use  of  buildings  is  constantly 
changing  and  expanding,  it  would  be  wise  to  look  ahead  a  few  years,  and 
if  possible,  prepare  foundations  to  carry  a  taller  and  more  elaborate  struc- 
ture than  may  be  called  for  at  the  present  time.  It  may  be  cheaper  to  do 
this  than  to  wreck  and  remove  a  building  of  this  nature. 


[126] 


I'.ILUE  OF  COXCRETE  AS  A  STRUCTURAL  MATERIAL 

CONCRETE    CONSTRUCTION,    RAPID, 

ECONOMICAL    AND    EASY 

By 

Chester  J.  Hogue,  C.  E. 

[Constructing  Engineer,    Boston,   Mass.] 

Reinforced  concrete  of  all  methods  of  building  construction,  seems 
to  be  attracting  the  most  attention  just  now,  and  the  design  of  reinforced 
concrete  certainly  furnishes,  at  this  time,  the  best  field  for  discussion  of 
any  branch  of  structural  engineering. 

Reinforced  concrete  factory  construction,  from  its  ease  and  economy 
of  execution,  rapidity  of  erection  and  fireproof  qualities  seems  to  be  the 
most  distinctive  development  of  this  form  of  construction,  and  in  a  short 
description  of  a  typical  concrete  factory  building  the  writer  may  mention 
briefly  the  principal  points  of  interest  and  advantage  in  this  particular 
method  of  building. 

On  the  side  of  economy,  the  company  with  which  the  writer  is  con- 
nected has  this  year,  by  careful  laying  out  of  the  work  and  study  of  the 
wood  forms,  proven  beyond  a  doubt  that  a  building  of  this  construction 
can  be  built  at  the  same  cost  as  one  with  brick  outside  walls  and  wood- 
framed  mill  construction  interior,  and  sometimes  for  even  less  if  the  build- 
ing is  high  and  the  loads  are  great.  In  general,  economy  in  design  lies  in 
using  slabs  of  8,  10  or  1 2-foot  span,  supported  by  lines  of  beams  in  one 
direction  only,  these  beams  resting  directly  on  columns  with  no  girders; 
but  when  a  wider  spacing  of  columns  is  required,  economy  is  gained  by 
using  a  slab  of  minimum  thickness,  say  3  inches,  if  the  finished  floor  is  to 
be  of  wood  on  top  of  the  concrete,  or  4  inches,  if  the  finished  floor  is  to 
be  of  granolithic  laid  at  the  same  time  and  as  a  part  of  the  floor,  spacing 
the  beams  as  closely  together  as  this  slab  will  require,  and  framing  the 
beams  into  girders  at  the  third  or  quarter  points. 

In  construction,  the  great  point  in  saving  of  cost  is  in  uniformity  of 
detail  and  in  making  the  wood  forms  carefully  at  first  in  units,  and  then 
using  the  units  over  and  over  again  as  many  times  as  possible.  As  for 
speed,  we  can  safely  guarantee  to  complete  a  building  at  the  rate  of  from 
eight  to  ten  days  a  story,  and  we  have  this  year  begun  and  completed  build- 
ings while  other  buildings  of  equal  size  were  waiting  for  their  steel  frames 
to  be  fabricated  and  erected. 

It  is  shown  beyond  doubt  that  in  recent  fires  and  earthquakes  buildings 
constructed  wholly  or  in  part  of  reinforced  concrete  gave  the  best  account 
of  themselves ;  if  properly  built  there  is  nothing  to  rot  or  rust ;  without  hol- 
low spaces  there  are  no  retreats  for  dust,  dirt  or  vermin. 

One  point,  however,  shown  by  a  number  of  recent  failures,  sounds  a 

[127] 


REINFORCED  CONCRETE 


note  oi  warning,  quite  independently  of  the  feeling  of  those  who  have  put 
years  of  study  into  this  work,  that  they  alone  should  he  trusted  to  do  it,  that 
unless  engineers  and  architects  are  themselves  experts  in  reinforced  concrete 
design  and  construction  and  wish  to  give  their  work  very  careful  super- 
vision, they  should  be  extremely  careful  that  the  men  into  whose  hands 
they  intrust  the  erection  of  their  buildings  should  know  how  to  design 
them,  how  to  build  them,  and  should  care  to  do  them  right,  and  both  they 
and  owners  should  realize  that  first  cost  does  not  always  mean  ultimate 
economy. 

There  are  two  types  of  reinforced  concrete  factory  construction,  the 
one    with   concrete   outside   bearing   walls   with   few    openings,   the   other 
[128] 


VALUE  OF  CONCRETE  AS  A  STRUCTURAL  MATERIAL 

the  skeleton  type  of  constructing,  the  walls  being  simply  filling  in  panels 
ouilt  afterwards.  It  is  the  latter  type  in  which  the  writer  is  particularly 
interested,  because  it  is  the  easier  to  build  and  the  more  economical. 

The  illustration  of  a  part  section  through  a  typical  building  of  this 
sort  will  serve  to  call  attention  to  the  following  points: 

The  column  and  pilaster  footings  only  need  go  down  to  a  solid  bear- 
ing unless  an  excavated  basement  is  required.  Where  there  is  a  basement, 
light  walls  reinforced  horizontally  from  column  to  column,  or  verti- 
cally from  the  basement  floor  to  the  first  floor  will  retain  the  earth,  the 
reactions  being  taken  by  the  columns  or  by  the  basement  and  first  floors, 
while  the  walls  may  be  reinforced  to  carry  themselves  from  footing  to 
footing,  requiring  no  foundations  of  their  own ;  where  there  is  no  base- 
ment, the  outside  walls  need  only  go  far  enough  down  to  prevent  frost 
'working  in  under  them,  with  possibly  a  shallow  trench  filled  with  cinders 
lor  gravel  underneath,  and  can  be  reinforced  to  carry  themselves  from  pier 
to  pier,  and  to  support  the  walls  above.  By  building  the  footings  first 
and  carefully  filling,  setting  and  leveling  the  earth,  and  laying  the  floor  on 
the  ground,  the  shores  to  support  the  false  work  can  be  cut  of  even  length, 
and  there  will  be  a  good  even  surface  to  shore  from.  Columns  and  floors 
are  built  first,  as  in  skeleton  steel  construction,  and  the  outside  panel 
walls  are  self-supporting,  but  not  weight-bearing,  and  are  built  in  between 
the  pilasters  entirely  independently  of  the  floors,  and,  at  a  later  time,  fur- 
nishing a  convenient  method  of  keeping  the  concrete  gang  busy  while 
the  concrete  floors  are  setting  or  the  wood  forms  are  being  shifted  from 
floor  to  floor,  or  when  the  weather  is  too  wet  or  too  cold  to  safely  permit 
the  laying  of  the  more  important  work  of  the  floor  construction. 

There  has  been  a  tremendous  development  in  this  class  of  buildings 
of  late,  and  probably  half  of  the  work  in  reinforced  concrete  this  year 
has  been  of  this  sort,  while  the  prospects  for  the  future  are  still  better. 


SPEED     IN     THE     ERECTION     OF    CON- 
CRETE   BUILDINGS 

,    . ;       By  ';   .;       |||;J 

J.   G.   Ellendt 

[Superintendent  of  Concrete  Construction  for  Frank  B.  Gilbreth] 

Modern  and  up  to  date  manufacturing  concerns  find  it  necessary  fre- 
quently to  increase  the  capacity  of  their  plants  at  very  short  notice.  When 
this  occurs  new  buildings  and  machinery  are  wanted  rapidly.  The  produc- 
tion of  things  is  those  turned  over  to  capable  and  energetic  contractors  who 
are  able  to  get  them  in  spite  of  difficulties.  To  battle  existing  conditions 
and  produce  results  at  a  minimum  and  specified  time. 

The  manufacturer  regulates  his  output  accordingly,  promises  deliveries 

[129] 


REIXFORCED  COX CRETE 


UNDERWRITERS'  UNIT    FRAME    REINFORCEMENT    EMPLOYED    IN    THE    CONSTRUCTION    OF    THE 
VALE    &    TOWNE    BUILDINGS,    AT    STAMFORD,    CONN. 

and  makes  contracts,  dependent  upon  having  his  additional  plant  in  opera- 
tion at  that  specified  time.  It  is  easily  seen  that  it  is  of  vital  importance 
first  of  all  to  look  for  speed  in  his  undertaking  and  also  get  the  very  best 
style  of  construction  in  his  buildings  and  those  most  suitable  for  his  purpose. 
The  Yale  &  Towne  Manufacturing  Co.,  of  Stamford,  Conn.,  recently  had 
the  above  conditions  to  meet.  Careful  consideration  and  investigation  of  the 
style  of  construction  to  be  used  for  their  new  building  convinced  them  that 
reinforced  concrete  construction  was  not  only  more  economical  but  superior 
in  every  respect  to  their  old  mill  constructed  buildings.  It  was  decided  there- 
fore that  two  of  their  new  buildings,  one  60  x  190,  and  one  50  x  60,  both  five 
stories,  were  to  be  of  reinforced  concrete  construction,  while  the  third, 
60  x  190,  also  five  stories,  was  to  be  of  mill  construction.  This  latter  was 
intended  to  save  time.  As  an  option  on  the  necessarv  lumber  had  been 
obtained  with  prospects  of  good  deliveries. 

Actual  building  operations  were  started  the  latter  part  of  February  on  all 
buildings.  While  the  architects  were  still  designing  the  buildings  and  getting 
ready  their  plans,  all  the  foundations  were  put  in,  from  preliminary  sketches 
and  information.  While  this  was  going  on  and  while  the  plans  were  being 
completed,  all  preparations  for  the  superstructure  were  made.  Materials  were 
rushed  to  the  building  site  and  the  concrete  mixing  plant  installed.  A 
temporary  carpenter  shop  with  power  saws,  planer,  drills  and  other  nec- 
essary machinery  was  put  in  operation  and  forms  and  centering  prepared 
for  two  floors  of  each  of  the  reinforced  concrete  buildings. 
[130] 


VALUE  OF  CONCRETE  AS  A  STRUCTURAL  MATERIAL 

In  order  to  make  the  new  buildings  conform  in  appearance  with  the 
old  plant,  the  exterior  walls  were  designed  to  be  built  of  brick.  This  neces- 
sarily caused  another  possibility  of  slow  building  operations  for  the  concrete 
buildings,  as  it  is  a  well  known  fact  that  with  brick  layers  and  concrete  men 
operating  at  the  same  time,  not  only  care  must  be  exercised  in  keeping  har- 
mony amongst  the  opposing  trades,  but  to  work  them  continuously  without 
either  gang  ever  waiting  for  the  other.  In  the  erection  of  these  particular 
bulidings  these  points  were  carefully  studied,  and  worked  out  so  well  that 
actually  each  gang  was  driving  the  other. 

Brick  -work  was  first  started  on  the  larger  concrete  building,  and  while 
the  walls  were  being  laid  for  the  first  story  the  false  work  erectors  were  set- 
ting forms.  Both  forces  were  concentrated  at  one  end  of  the  building  and 
several  bays  finished  to  receive  the  reinforcement  rods  for  girders,  beams  and 
slabs. 

Due  to  the  style  of  reinforcement  used — the  Underwriters'  unit  frame — 
the  time  for  placing  the  reinforcement  was  cut  down  to  a  minimum  and  the 
exact  location  of  the  reinforcement  assured  by  means  of  the  separators  which 
hold  the  various  rods  in  their  respective  positions.  The  slab  reinforce- 
ment was  also  made  up  of  units  of  such  size  that  four  men  could  handle 
them.  All  of  these  units  were  bent  and  assembled  at  a  factory  and 
delivered  on  cars  near  the  building  site  ready  to  be  placed. 

As  the  placing  of  the  reinforcement  took  but  a  trivial  amount  of  time, 
the  concreting  gang  followed  the  heels  of  the  bricklayers  and  false-work 
erectors  without  interruption.  It  was  found  that  an  entire  floor  could  be  con- 
creted in  four  days,  but  that  the  brickwork  and  false  work  erection  could  not 
be  done  in  less  than  eight  days.  This  practically  set  the  time  limit  on  the 
construction  and  the  remaining  stories  were  erected  at  this  rate. 

The  smaller  concrete  building  was  being  erected  at  the  same  time  with 
its  own  gang  of  bricklayers  and  false  work  erectors,  but  the  same  concrete 
gang  took  care  of  it.  This  arrangement  kept  every  gang  on  the  jump  with 
the  advantage  of  each  gang  driving  the  other  with  intent  to  show  the  possible 
weakness  of  the  other.  Aside  from  an  unavoidable  strike  on  the  part  of 
the  bricklayers  for  a  few  days,  the  entire  operation  ran  as  smoothly  as 
intended. 

The  erection  of  the  mill  construction  was  going  on  at  the  same  time. 
The  time  required  to  build  a  story  there  was  found  to  be  just  as  long  as  for 
the  reinforced  concrete  buildings.  .A  slight  saving  "of  time,  however,  was 
experienced  as  the  last  floors  could  .be  occupied  immediately,  whereas  in  the 
concrete  buildings  the  centering  had  to  remain  for  a  required  time. 

Sixty-four  days  elapsed  from  the  time  when  ground  was  broken  for  the 
buildings  until  they  were  ready  for  operation.  The  entire  work  was  done  by 
Frank  B.  Gilbreth,  34  W.  26th  St.,  New  York,  on  the  c«st-plus-a-fixed-sum 
basis ;  the  concrete  work  was  executed  by  the  Gilbreth  concrete  department, 
the  Underwriters'  Engineering  and  Construction  Co.,  1170  Broadway,  N.  Y. 

[131] 


REINFORCED  CONCRETE 

REINFORCED    CONCRETE    MILL 

BUILDINGS 

By 

A.  E.  Lindau,  Associate  Am.  Soc.  C.  E. 

To  the  uninitiated  the  whole  subject  of  reinforced  concrete  seems  a 
hopeless  tangle.  Each  individual  designer  appears  to  have  his  own  theo- 
ries and  methods  of  construction,  new  formulae  are  continually  being  pub- 
lished by  the  technical  journals,  and  even  the  most  reliable  experiments 
have  so  wide  a  range  of  variation  that  the  inference  is  sometimes  made 
that  results  can  be  made  to  fit  any  theory  by  a  little  manipulation.  This 
confusion  has  arisen,  no  doubt,  to  a  certain  extent,  because  of  mystery 
with  which  so  many  of  these  so-called  systems  are  surrounded,  and  fur- 
ther, because  of  the  changes  which  have  naturally  taken  place  during  the 
rapid  development  of  this  comparatively  new  form  of  construction. 

As  a  matter  of  fact,  however,  there  is  not  nearly  so  great  a  difference 
between  the  various  theories  and  formulae  as  may  be  supposed,  the  differ- 
ence being  principally  a  question  of  unit  stresses,  a  condition  that  prevails 
in  the  domain  of  structural  steel  design  to  an  almost  equal  degree,  and 
if  the  results  of  experiments  on  reinforced  concrete  beams  are  reduced  to 
the  same  basis  with  respect  to  the  percentage  of  reinforcement,  elastic 
limit  of  the  steel  and  strength  of  the  concrete,  the  average  result  will  very 
closely  approximate  the  values  obtained  by  computation  when  the  loading 
is  such  that  the  bending  moment  can  be  definitely  determined. 

The  design  of  mill  buildings  differs  from  that  of  ordinary  warehouse 
construction,  in  so  far  as  length  of  span  of  girders,  vibration  and  shock 
of  sudden  loading  is  concerned.  Reinforced  concrete  girders  can  generally 
be  made  of  sufficient  span  to  satisfy  ordinary  requirements.  If  necessary, 
some  girders  and  exceptionally  heavy  beams  can  be  made  of  steel  protected 
by  concrete.  As  to  vibration  and  shock,  it  seems  that  reinforced  concrete 
can  more  than  hold  its  own.  Many  western  railroads  are  using  compara- 
tively thin  reinforced  concrete  floors  immediately  under  a  foot  or  so  of 
ballast.  The  vibration  and  shock  in  a  5O-foot  or  6o-foot  girder  with  a 
train  speeding  over  it  60  to  70  miles  per  hour  must  be  very  much  greater 
than  any  that  is  likely  to  occur  in  a  mill  building.  In  an  office  building 
recently  erected  several  concrete  lintels,  weighing  approximately  a  ton 
each,  were  accidentally  dropped  from  a  height  of  five  or  six  stories,  on  n 
4-inch  slab  spanning  12  feet,  without  in  the  least  injuring  the  slab,  while 
the  lintels  were  entirely  .demolished.  In  another  instance,  a  35-foot  or 
40- foot  length  of  1 8-inch  water  pipe  fell,  during  erection,  on  a  reinforced 
concrete  floor  without  doing  any  visible  damage  to  the  floor. 

[132] 


MISCELLANEOUS  ILLUSTRATIONS 


<    w 

M  a 


[133] 


REINFORCED  CONCRETE 


[134] 


MISCELLANEOUS  ILLUSTRATIONS 


20-TQN     PRESSES    RESTING    ON    A     CONCRETE    FLOOR,'     KETTERLINUS     BUILDING.     PHILADELPHIA 


REINFORCED    CONCRETE    WAREHOUSE    OF    THE    VICTOR    TALKING     MACHINE    CO., 
DALLINGER     &     PERROT.     ARCHITECTS 


[135] 


REINFORCED  CONCRETE 


§ 

«3      W 

w    o 

o 


H     W 

§       IH 


£  ? 

w  3 

u  -^ 

«  g 


o    g 

£    fe 

O     fe 


en 

<  8 
fc  « 


ffi 

en 

en     y 
M     O 


B 


MISCELLAXEOUS  ILLUSTRATIONS 


LAYING     EXPANDED     METAL    ON     CENTERING,     FAIRBANKS     CO.     WAREHOUSE,     BALTIMORE,     MD. 


EXTERIOR  VIEW    OF   FAIRBANKS    CO.    WAREHOUSE,    SHOWING    STYLE   OF   CONSTRUCTION 


[137] 


REINFORCED  CONCRETE 


DETAIL    OF    CORNER    CONSTRUCTION    IN    THE    REINFORCED    CONCRETE    WAREHOUSE    ERECTED    FOR 
THE    FAIRBANKS    CO.    AT    BALTIMORE,    MD. 


1381 


MISCELLANEOUS  ILLUSTRATIONS 


[I39l 


TEN-STORY   REINFORCED    CONCRETE   BUILDING    FOR   BERNARD   GLOEKLER    &    CO.,    PITTSBURG  J 
BALLINGER    &    PERROT,    ARCHITECTS 


CONCRETE    RETAINING    WALL    ON    LEXINGTON    AVE.,    NEW    YORK,    SHOWING    DETAILS    OF    CON- 
STRUCTION 


MISCELLANEOUS  ILLUSTRATIONS 


MOLDING    REINFORCED    CONCRETE    SLABS    FOR    THE    ROOF    OF    THE    CHITTENDEN    POWER    HOUSE, 

RUTLAND,  VT. 


•CONCRETE    STEEL    POWER      HOUSE    OF     THE      MANILA      ELECTRIC      RAILWAY      AND      LIGHT      CO., 

MANILA,    P.    I. 

[HI] 


REINFORCED  CONCRETE 


THE    ROBERT     GAIR    FACTORY,     BROOKLYN,     N.     Y.,    AN     EXCELLENT     EXAMPLE     OF     REINFORCED 
CONCRETE    CONSTRUCTION.       BUILT    BY    THE    TURNER    CONSTRUCTION     CO.,    N.     Y. 


[142] 


MISCELLANEOUS  ILLUSTRATIONS 


BIRDSEYE    VIEW    OF    THE    PRELIMINARY    ERECTION    OF     STEEL    REINFORCEMENT    FOR    COLUMNS 
AND   GIRDERS    IN    THE    PUGH    POWER    BUILDING,    CINCINNATI,    OHIO. 


VIEW    OF    THE    PUGH    POWER    BUILDING,    SHOWING    STRUCTURE    FINISHED    UP    TO    THE    SIXTH 
FLOOR.       THE    DIMENSIONS    OF    THE    BUILDING    ARE    68    FEET    FRONT,    335    FEET    LENGTH    AND 

TEN    STORIES    IN    HEIGHT 

[143] 


REINFORCED  CONCRETE 


VIEW    OF    PUGH     POWER    BUILDING,    CINCINNATI,    OHIO,     SHOWING     METHOD     OF     FORM     CON- 
STRUCTION.     THIS   BUILDING  IS   AN  EXCELLENT  TYPE  OF  REINFORCED  CONCRETE  CONSTRUCTION. 


[144] 


MISCELLANEOUS  ILLUSTRATIONS 


INTERIOR   OF    THE    GOVERNMENT    COAL    POCKETS,    BRADFORD,    R.    I.       FORMS    AND    ELECTRICALLY- 
WELDED    FABRIC    REINFORCEMENT    IN    PLACE    READY    FOR    THE    CONCRETE 


FINISHED  INTERIOR  VIEW  OF  GOVERNMENT  COAL  POCKETS   AT  BRADFOBD,  R.   I,    SHOWING   CON- 
CRETE IN   PLACE 

[145] 


REINFORCED  CONCRETE 


GENERAL    VIEW    OF    THE   REINFORCED    CONCRETE    POWER    HOUSE    AND    PULP    MILL    IN    THE    BED 

OF  THE  ANDROSCOGGIN  RIVER   AT  BERLIN,    N.    H.,    INTERNATIONAL   PAPER  CO.,   OWNERS.      THIS 

BUILDING  WAS   BUILT  DURING  A   SEVERE   NEW    ENGLAND   WINTER,    SHOWING   THE   POSSIBILITY 

OF  THE  USE  OF  CONCRETE  IN   THE   WINTER  SEASON 


[I46] 


MISCELLANEOUS  ILLUSTRATIONS 


MISCELLANEOUS  ILLUSTRATIONS 


THE   MCNULTY   BUILDING,   354~6   WEST   52ND    ST.,    N.    Y.,    BUILT    OF    REINFORCED    CONCRETE   BY 
TUCKER    &    VINTON,    N.    Y.      UNDER    SIDE   OF   TENTH    FLOOR    SETTLING.       FORMS    REMOVED. 


[I48] 


MISCELLANEO  US  ILL  USTRA  TIONS 


VIEW   OF  THE  CENTERING   IN  THE   MCNULTY  BUILDING,   N.   Y.,  WHICH    SUPPORTS   THE  TENTH 
FLOOR    WHILE    THE    CONCRETE    IS    SETTING 


[149] 


REINFORCED  CONCRETE 


[ISO] 


MISCELLANEOUS  ILLUSTRATIONS 


REINFORCED    CONCRETE    ADDITION    TO   THE   E.    R.    THOMAS    MOTOR    CO/S    PLANT    AT    BUFFALO 
KAHN    SYSTEM    USED    THROUGHOUT 


INTERIOR    VIEW   OF    E.    R.    THOMAS    MOTOR    CAR   CO.    PLANT,    BUFFALO,    N.    Y.       KAHN    SYSTEM 

USED  THROUGHOUT 


REINFORCED  CONCRETE 


FRONT  ELEVATION  OF  GARFORD  CO.   FACTORY,  ELYRIA,  OHIO,   KAHN    SYSTEM    USED   THROUGHOUT 


ONE  OF  FIVE  BUILDINGS    JUST  COMPLETED     FOR     THE     GLAZIER     STOVE     CO.,     CHELSEA,     MICH. 
KAHN    SYSTEM    USED    THROUGHOUT 

[152] 


UlSii'.msmr  O2  CALIFORNI      ;  TBRARY 
This  book  is  DUE  on  the  last  date  stamped  below. 

Fine  schedule:  25  cents  on  first  day  overdue 

50  cents  on  fourth  day  overdue 
One  dollar  on  seventh  day  overdue. 


ENGINEERING  LIEJRARY 


LD  21-100m-12,'46(A2012sl6)4120 


ATI 


U.C.  BERKELEY  LIBRARIES 


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Engineering 
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UNIVERSITY  OF  CALIFORNIA  LIBRARY 


